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963 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Eugene Syromiatnikov
|
a966dcfe15 |
clone3: add build-time CLONE_ARGS_SIZE_VER* validity checks
CLONE_ARGS_SIZE_VER* macros are defined explicitly and not via the offsets of the relevant struct clone_args fields, which makes it rather error-prone, so it probably makes sense to add some compile-time checks for them (including the one that breaks on struct clone_args extension as a reminder to add a relevant size macro and a similar check). Function copy_clone_args_from_user seems to be a good place for such checks. Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200412202658.GA31499@asgard.redhat.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
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Eugene Syromiatnikov
|
62173872ca |
clone3: add a check for the user struct size if CLONE_INTO_CGROUP is set
Passing CLONE_INTO_CGROUP with an under-sized structure (that doesn't properly contain cgroup field) seems like garbage input, especially considering the fact that fd 0 is a valid descriptor. Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200412203123.GA5869@asgard.redhat.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
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Eugene Syromiatnikov
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e82a118f57 |
clone3: fix cgroup argument sanity check
Checking that cgroup field value of struct clone_args is less than 0
is useless, as it is defined as unsigned 64-bit integer. Moreover,
it doesn't catch the situations where its higher bits are lost during
the assignment to the cgroup field of the cgroup field of the internal
struct kernel_clone_args (where it is declared as signed 32-bit
integer), so it is still possible to pass garbage there. A check
against INT_MAX solves both these issues.
Fixes:
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Li Xinhai
|
e39a4b332d |
mm: set vm_next and vm_prev to NULL in vm_area_dup()
Set ->vm_next and ->vm_prev to NULL to prevent potential misuse from the new duplicated vma. Currently, only in fork path there are misuse for handling anon_vma. No other bugs been revealed with this patch applied. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@redhat.com> Link: http://lkml.kernel.org/r/1581150928-3214-4-git-send-email-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Li Xinhai
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93949bb21b |
mm: don't prepare anon_vma if vma has VM_WIPEONFORK
Patch series "mm: Fix misuse of parent anon_vma in dup_mmap path".
This patchset fixes the misuse of parenet anon_vma, which mainly caused by
child vma's vm_next and vm_prev are left same as its parent after
duplicate vma. Finally, code reached parent vma's neighbor by referring
pointer of child vma and executed wrong logic.
The first two patches fix relevant issues, and the third patch sets
vm_next and vm_prev to NULL when duplicate vma to prevent potential misuse
in future.
Effects of the first bug is that causes rmap code to check both parent and
child's page table, although a page couldn't be mapped by both parent and
child, because child vma has WIPEONFORK so all pages mapped by child are
'new' and not relevant to parent.
Effects of the second bug is that the relationship of anon_vma of parent
and child are totallyconvoluted. It would cause 'son', 'grandson', ...,
etc, to share 'parent' anon_vma, which disobey the design rule of reusing
anon_vma (the rule to be followed is that reusing should among vma of same
process, and vma should not gone through fork).
So, both issues should cause unnecessary rmap walking and have unexpected
complexity.
These two issues would not be directly visible, I used debugging code to
check the anon_vma pointers of parent and child when inspecting the
suspicious implementation of issue #2, then find the problem.
This patch (of 3):
In dup_mmap(), anon_vma_prepare() is called for vma has VM_WIPEONFORK, and
parameter 'tmp' (i.e., the new vma of child) has same ->vm_next and
->vm_prev as its parent vma. That allows anon_vma used by parent been
mistakenly shared by child (find_mergeable_anon_vma() will do this reuse
work).
Besides this issue, call anon_vma_prepare() should be avoided because we
don't copy page for this vma. Preparing anon_vma will be handled during
fault.
Fixes:
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Linus Torvalds
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d883600523 |
Merge branch 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: - Christian extended clone3 so that processes can be spawned into cgroups directly. This is not only neat in terms of semantics but also avoids grabbing the global cgroup_threadgroup_rwsem for migration. - Daniel added !root xattr support to cgroupfs. Userland already uses xattrs on cgroupfs for bookkeeping. This will allow delegated cgroups to support such usages. - Prateek tried to make cpuset hotplug handling synchronous but that led to possible deadlock scenarios. Reverted. - Other minor changes including release_agent_path handling cleanup. * 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: docs: cgroup-v1: Document the cpuset_v2_mode mount option Revert "cpuset: Make cpuset hotplug synchronous" cgroupfs: Support user xattrs kernfs: Add option to enable user xattrs kernfs: Add removed_size out param for simple_xattr_set kernfs: kvmalloc xattr value instead of kmalloc cgroup: Restructure release_agent_path handling selftests/cgroup: add tests for cloning into cgroups clone3: allow spawning processes into cgroups cgroup: add cgroup_may_write() helper cgroup: refactor fork helpers cgroup: add cgroup_get_from_file() helper cgroup: unify attach permission checking cpuset: Make cpuset hotplug synchronous cgroup.c: Use built-in RCU list checking kselftest/cgroup: add cgroup destruction test cgroup: Clean up css_set task traversal |
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Linus Torvalds
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6cad420cc6 |
Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton:
"A large amount of MM, plenty more to come.
Subsystems affected by this patch series:
- tools
- kthread
- kbuild
- scripts
- ocfs2
- vfs
- mm: slub, kmemleak, pagecache, gup, swap, memcg, pagemap, mremap,
sparsemem, kasan, pagealloc, vmscan, compaction, mempolicy,
hugetlbfs, hugetlb"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (155 commits)
include/linux/huge_mm.h: check PageTail in hpage_nr_pages even when !THP
mm/hugetlb: fix build failure with HUGETLB_PAGE but not HUGEBTLBFS
selftests/vm: fix map_hugetlb length used for testing read and write
mm/hugetlb: remove unnecessary memory fetch in PageHeadHuge()
mm/hugetlb.c: clean code by removing unnecessary initialization
hugetlb_cgroup: add hugetlb_cgroup reservation docs
hugetlb_cgroup: add hugetlb_cgroup reservation tests
hugetlb: support file_region coalescing again
hugetlb_cgroup: support noreserve mappings
hugetlb_cgroup: add accounting for shared mappings
hugetlb: disable region_add file_region coalescing
hugetlb_cgroup: add reservation accounting for private mappings
mm/hugetlb_cgroup: fix hugetlb_cgroup migration
hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations
hugetlb_cgroup: add hugetlb_cgroup reservation counter
hugetlbfs: Use i_mmap_rwsem to address page fault/truncate race
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
mm/memblock.c: remove redundant assignment to variable max_addr
mm: mempolicy: require at least one nodeid for MPOL_PREFERRED
mm: mempolicy: use VM_BUG_ON_VMA in queue_pages_test_walk()
...
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Linus Torvalds
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d987ca1c6b |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull exec/proc updates from Eric Biederman: "This contains two significant pieces of work: the work to sort out proc_flush_task, and the work to solve a deadlock between strace and exec. Fixing proc_flush_task so that it no longer requires a persistent mount makes improvements to proc possible. The removal of the persistent mount solves an old regression that that caused the hidepid mount option to only work on remount not on mount. The regression was found and reported by the Android folks. This further allows Alexey Gladkov's work making proc mount options specific to an individual mount of proc to move forward. The work on exec starts solving a long standing issue with exec that it takes mutexes of blocking userspace applications, which makes exec extremely deadlock prone. For the moment this adds a second mutex with a narrower scope that handles all of the easy cases. Which makes the tricky cases easy to spot. With a little luck the code to solve those deadlocks will be ready by next merge window" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (25 commits) signal: Extend exec_id to 64bits pidfd: Use new infrastructure to fix deadlocks in execve perf: Use new infrastructure to fix deadlocks in execve proc: io_accounting: Use new infrastructure to fix deadlocks in execve proc: Use new infrastructure to fix deadlocks in execve kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve kernel: doc: remove outdated comment cred.c mm: docs: Fix a comment in process_vm_rw_core selftests/ptrace: add test cases for dead-locks exec: Fix a deadlock in strace exec: Add exec_update_mutex to replace cred_guard_mutex exec: Move exec_mmap right after de_thread in flush_old_exec exec: Move cleanup of posix timers on exec out of de_thread exec: Factor unshare_sighand out of de_thread and call it separately exec: Only compute current once in flush_old_exec pid: Improve the comment about waiting in zap_pid_ns_processes proc: Remove the now unnecessary internal mount of proc uml: Create a private mount of proc for mconsole uml: Don't consult current to find the proc_mnt in mconsole_proc proc: Use a list of inodes to flush from proc ... |
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Roman Gushchin
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f4b00eab50 |
mm: kmem: rename memcg_kmem_(un)charge() into memcg_kmem_(un)charge_page()
Rename (__)memcg_kmem_(un)charge() into (__)memcg_kmem_(un)charge_page() to better reflect what they are actually doing: 1) call __memcg_kmem_(un)charge_memcg() to actually charge or uncharge the current memcg 2) set or clear the PageKmemcg flag Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Link: http://lkml.kernel.org/r/20200109202659.752357-4-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Roman Gushchin
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8380ce4790 |
mm: fork: fix kernel_stack memcg stats for various stack implementations
Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio the
space for task stacks can be allocated using __vmalloc_node_range(),
alloc_pages_node() and kmem_cache_alloc_node().
In the first and the second cases page->mem_cgroup pointer is set, but
in the third it's not: memcg membership of a slab page should be
determined using the memcg_from_slab_page() function, which looks at
page->slab_cache->memcg_params.memcg . In this case, using
mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
page->mem_cgroup pointer is NULL even for pages charged to a non-root
memory cgroup.
It can lead to kernel_stack per-memcg counters permanently showing 0 on
some architectures (depending on the configuration).
In order to fix it, let's introduce a mod_memcg_obj_state() helper,
which takes a pointer to a kernel object as a first argument, uses
mem_cgroup_from_obj() to get a RCU-protected memcg pointer and calls
mod_memcg_state(). It allows to handle all possible configurations
(CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE values) without
spilling any memcg/kmem specifics into fork.c .
Note: This is a special version of the patch created for stable
backports. It contains code from the following two patches:
- mm: memcg/slab: introduce mem_cgroup_from_obj()
- mm: fork: fix kernel_stack memcg stats for various stack implementations
[guro@fb.com: introduce mem_cgroup_from_obj()]
Link: http://lkml.kernel.org/r/20200324004221.GA36662@carbon.dhcp.thefacebook.com
Fixes:
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Bernd Edlinger
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3e74fabd39 |
exec: Fix a deadlock in strace
This fixes a deadlock in the tracer when tracing a multi-threaded application that calls execve while more than one thread are running. I observed that when running strace on the gcc test suite, it always blocks after a while, when expect calls execve, because other threads have to be terminated. They send ptrace events, but the strace is no longer able to respond, since it is blocked in vm_access. The deadlock is always happening when strace needs to access the tracees process mmap, while another thread in the tracee starts to execve a child process, but that cannot continue until the PTRACE_EVENT_EXIT is handled and the WIFEXITED event is received: strace D 0 30614 30584 0x00000000 Call Trace: __schedule+0x3ce/0x6e0 schedule+0x5c/0xd0 schedule_preempt_disabled+0x15/0x20 __mutex_lock.isra.13+0x1ec/0x520 __mutex_lock_killable_slowpath+0x13/0x20 mutex_lock_killable+0x28/0x30 mm_access+0x27/0xa0 process_vm_rw_core.isra.3+0xff/0x550 process_vm_rw+0xdd/0xf0 __x64_sys_process_vm_readv+0x31/0x40 do_syscall_64+0x64/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9 expect D 0 31933 30876 0x80004003 Call Trace: __schedule+0x3ce/0x6e0 schedule+0x5c/0xd0 flush_old_exec+0xc4/0x770 load_elf_binary+0x35a/0x16c0 search_binary_handler+0x97/0x1d0 __do_execve_file.isra.40+0x5d4/0x8a0 __x64_sys_execve+0x49/0x60 do_syscall_64+0x64/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9 This changes mm_access to use the new exec_update_mutex instead of cred_guard_mutex. This patch is based on the following patch by Eric W. Biederman: "[PATCH 0/5] Infrastructure to allow fixing exec deadlocks" Link: https://lore.kernel.org/lkml/87v9ne5y4y.fsf_-_@x220.int.ebiederm.org/ Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> |
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Eric W. Biederman
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eea9673250 |
exec: Add exec_update_mutex to replace cred_guard_mutex
The cred_guard_mutex is problematic as it is held over possibly indefinite waits for userspace. The possible indefinite waits for userspace that I have identified are: The cred_guard_mutex is held in PTRACE_EVENT_EXIT waiting for the tracer. The cred_guard_mutex is held over "put_user(0, tsk->clear_child_tid)" in exit_mm(). The cred_guard_mutex is held over "get_user(futex_offset, ...") in exit_robust_list. The cred_guard_mutex held over copy_strings. The functions get_user and put_user can trigger a page fault which can potentially wait indefinitely in the case of userfaultfd or if userspace implements part of the page fault path. In any of those cases the userspace process that the kernel is waiting for might make a different system call that winds up taking the cred_guard_mutex and result in deadlock. Holding a mutex over any of those possibly indefinite waits for userspace does not appear necessary. Add exec_update_mutex that will just cover updating the process during exec where the permissions and the objects pointed to by the task struct may be out of sync. The plan is to switch the users of cred_guard_mutex to exec_update_mutex one by one. This lets us move forward while still being careful and not introducing any regressions. Link: https://lore.kernel.org/lkml/20160921152946.GA24210@dhcp22.suse.cz/ Link: https://lore.kernel.org/lkml/AM6PR03MB5170B06F3A2B75EFB98D071AE4E60@AM6PR03MB5170.eurprd03.prod.outlook.com/ Link: https://lore.kernel.org/linux-fsdevel/20161102181806.GB1112@redhat.com/ Link: https://lore.kernel.org/lkml/20160923095031.GA14923@redhat.com/ Link: https://lore.kernel.org/lkml/20170213141452.GA30203@redhat.com/ Ref: 45c1a159b85b ("Add PTRACE_O_TRACEVFORKDONE and PTRACE_O_TRACEEXIT facilities.") Ref: 456f17cd1a28 ("[PATCH] user-vm-unlock-2.5.31-A2") Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> |
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Madhuparna Bhowmik
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0c282b068e
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fork: Use RCU_INIT_POINTER() instead of rcu_access_pointer()
Use RCU_INIT_POINTER() instead of rcu_access_pointer() in copy_sighand(). Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> [christian.brauner@ubuntu.com: edit commit message] Link: https://lore.kernel.org/r/20200127175821.10833-1-madhuparnabhowmik10@gmail.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
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Christian Brauner
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ef2c41cf38 |
clone3: allow spawning processes into cgroups
This adds support for creating a process in a different cgroup than its parent. Callers can limit and account processes and threads right from the moment they are spawned: - A service manager can directly spawn new services into dedicated cgroups. - A process can be directly created in a frozen cgroup and will be frozen as well. - The initial accounting jitter experienced by process supervisors and daemons is eliminated with this. - Threaded applications or even thread implementations can choose to create a specific cgroup layout where each thread is spawned directly into a dedicated cgroup. This feature is limited to the unified hierarchy. Callers need to pass a directory file descriptor for the target cgroup. The caller can choose to pass an O_PATH file descriptor. All usual migration restrictions apply, i.e. there can be no processes in inner nodes. In general, creating a process directly in a target cgroup adheres to all migration restrictions. One of the biggest advantages of this feature is that CLONE_INTO_GROUP does not need to grab the write side of the cgroup cgroup_threadgroup_rwsem. This global lock makes moving tasks/threads around super expensive. With clone3() this lock is avoided. Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: cgroups@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Christian Brauner
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5a5cf5cb30 |
cgroup: refactor fork helpers
This refactors the fork helpers so they can be easily modified in the next patches. The patch just moves the cgroup threadgroup rwsem grab and release into the helpers. They don't need to be directly exposed in fork.c. Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: cgroups@vger.kernel.org Acked-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Tejun Heo <tj@kernel.org> |
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Linus Torvalds
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39bed42de2 |
hmm related patches for 5.6
This small series revises the names in mmu_notifier to make the code clearer and more readable. -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEfB7FMLh+8QxL+6i3OG33FX4gmxoFAl4wf2EACgkQOG33FX4g mxqrdw//XIexbXQqP4dUKFCFeI7Um6ZqYE6iVCQi6JEetpKxCR8BSrJsq6EP60Mg cVCKolISuudzOccz/liotg9SrwRlcO3mzucd8LJZG0v2FZMzQr0EKjst0RC4/xvK U2RxGvwLQ+XVR/3/l6hXyWyw7u28+F1RsfQMMX3kqR3qlcQachQ3k7oUINDIq2XH JkQcBV+XK0doXEp6VCCVKwuwEN7O5xSm8lAIHDNFZEEPre0iKxwatgWxdXFIWQek tRywwB7bRzFROBlDcoOQ0GDTqScr3bghz6vWU4GGv3avYkystKwy44ha6BzO2xQc ZNIo8AN9UFFhcmF531wklsXTCbxbxJAJAwdyIuQnKq5glw64EFnrjo2sxuL6s56h C1GHADtxDccv+nr2sKP/rFFeq9K3VqHDtjEdBOhReuB0Vp1YfVr17A4R8yAn8A+1 vm3IusoOq+g8qMYxRHEb+76/S//joaxAlFQkU5Gjn/0xsykP99YQSQFBjXmkzWlS IiHLf0HJiCCL8SHe4Wnyhyl1DUIIl38HQULqbFWZ8hK4ELhTd2KEuDxzT8q+v+v7 2M9nBVdRaw1kskGiFv+F7mb6c990CTEZO9B5fHpAjPRxeVkLYc06QfJY+hXbbu4c 6yzIvERRRlAviCmgb7G+3pLyBCKdvlIlCVsVOdxHXSRsl904BnA= =hhT0 -----END PGP SIGNATURE----- Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma Pull mmu_notifier updates from Jason Gunthorpe: "This small series revises the names in mmu_notifier to make the code clearer and more readable" * tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: mm/mmu_notifiers: Use 'interval_sub' as the variable for mmu_interval_notifier mm/mmu_notifiers: Use 'subscription' as the variable name for mmu_notifier mm/mmu_notifier: Rename struct mmu_notifier_mm to mmu_notifier_subscriptions |
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Linus Torvalds
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e279160f49 |
The timekeeping and timers departement provides:
- Time namespace support:
If a container migrates from one host to another then it expects that
clocks based on MONOTONIC and BOOTTIME are not subject to
disruption. Due to different boot time and non-suspended runtime these
clocks can differ significantly on two hosts, in the worst case time
goes backwards which is a violation of the POSIX requirements.
The time namespace addresses this problem. It allows to set offsets for
clock MONOTONIC and BOOTTIME once after creation and before tasks are
associated with the namespace. These offsets are taken into account by
timers and timekeeping including the VDSO.
Offsets for wall clock based clocks (REALTIME/TAI) are not provided by
this mechanism. While in theory possible, the overhead and code
complexity would be immense and not justified by the esoteric potential
use cases which were discussed at Plumbers '18.
The overhead for tasks in the root namespace (host time offsets = 0) is
in the noise and great effort was made to ensure that especially in the
VDSO. If time namespace is disabled in the kernel configuration the
code is compiled out.
Kudos to Andrei Vagin and Dmitry Sofanov who implemented this feature
and kept on for more than a year addressing review comments, finding
better solutions. A pleasant experience.
- Overhaul of the alarmtimer device dependency handling to ensure that
the init/suspend/resume ordering is correct.
- A new clocksource/event driver for Microchip PIT64
- Suspend/resume support for the Hyper-V clocksource
- The usual pile of fixes, updates and improvements mostly in the
driver code.
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Merge tag 'timers-core-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"The timekeeping and timers departement provides:
- Time namespace support:
If a container migrates from one host to another then it expects
that clocks based on MONOTONIC and BOOTTIME are not subject to
disruption. Due to different boot time and non-suspended runtime
these clocks can differ significantly on two hosts, in the worst
case time goes backwards which is a violation of the POSIX
requirements.
The time namespace addresses this problem. It allows to set offsets
for clock MONOTONIC and BOOTTIME once after creation and before
tasks are associated with the namespace. These offsets are taken
into account by timers and timekeeping including the VDSO.
Offsets for wall clock based clocks (REALTIME/TAI) are not provided
by this mechanism. While in theory possible, the overhead and code
complexity would be immense and not justified by the esoteric
potential use cases which were discussed at Plumbers '18.
The overhead for tasks in the root namespace (ie where host time
offsets = 0) is in the noise and great effort was made to ensure
that especially in the VDSO. If time namespace is disabled in the
kernel configuration the code is compiled out.
Kudos to Andrei Vagin and Dmitry Sofanov who implemented this
feature and kept on for more than a year addressing review
comments, finding better solutions. A pleasant experience.
- Overhaul of the alarmtimer device dependency handling to ensure
that the init/suspend/resume ordering is correct.
- A new clocksource/event driver for Microchip PIT64
- Suspend/resume support for the Hyper-V clocksource
- The usual pile of fixes, updates and improvements mostly in the
driver code"
* tag 'timers-core-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
alarmtimer: Make alarmtimer_get_rtcdev() a stub when CONFIG_RTC_CLASS=n
alarmtimer: Use wakeup source from alarmtimer platform device
alarmtimer: Make alarmtimer platform device child of RTC device
alarmtimer: Update alarmtimer_get_rtcdev() docs to reflect reality
hrtimer: Add missing sparse annotation for __run_timer()
lib/vdso: Only read hrtimer_res when needed in __cvdso_clock_getres()
MIPS: vdso: Define BUILD_VDSO32 when building a 32bit kernel
clocksource/drivers/hyper-v: Set TSC clocksource as default w/ InvariantTSC
clocksource/drivers/hyper-v: Untangle stimers and timesync from clocksources
clocksource/drivers/timer-microchip-pit64b: Fix sparse warning
clocksource/drivers/exynos_mct: Rename Exynos to lowercase
clocksource/drivers/timer-ti-dm: Fix uninitialized pointer access
clocksource/drivers/timer-ti-dm: Switch to platform_get_irq
clocksource/drivers/timer-ti-dm: Convert to devm_platform_ioremap_resource
clocksource/drivers/em_sti: Fix variable declaration in em_sti_probe
clocksource/drivers/em_sti: Convert to devm_platform_ioremap_resource
clocksource/drivers/bcm2835_timer: Fix memory leak of timer
clocksource/drivers/cadence-ttc: Use ttc driver as platform driver
clocksource/drivers/timer-microchip-pit64b: Add Microchip PIT64B support
clocksource/drivers/hyper-v: Reserve PAGE_SIZE space for tsc page
...
|
||
Jason Gunthorpe
|
984cfe4e25 |
mm/mmu_notifier: Rename struct mmu_notifier_mm to mmu_notifier_subscriptions
The name mmu_notifier_mm implies that the thing is a mm_struct pointer, and is difficult to abbreviate. The struct is actually holding the interval tree and hlist containing the notifiers subscribed to a mm. Use 'subscriptions' as the variable name for this struct instead of the really terrible and misleading 'mmn_mm'. Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> |
||
Andrei Vagin
|
769071ac9f |
ns: Introduce Time Namespace
Time Namespace isolates clock values.
The kernel provides access to several clocks CLOCK_REALTIME,
CLOCK_MONOTONIC, CLOCK_BOOTTIME, etc.
CLOCK_REALTIME
System-wide clock that measures real (i.e., wall-clock) time.
CLOCK_MONOTONIC
Clock that cannot be set and represents monotonic time since
some unspecified starting point.
CLOCK_BOOTTIME
Identical to CLOCK_MONOTONIC, except it also includes any time
that the system is suspended.
For many users, the time namespace means the ability to changes date and
time in a container (CLOCK_REALTIME). Providing per namespace notions of
CLOCK_REALTIME would be complex with a massive overhead, but has a dubious
value.
But in the context of checkpoint/restore functionality, monotonic and
boottime clocks become interesting. Both clocks are monotonic with
unspecified starting points. These clocks are widely used to measure time
slices and set timers. After restoring or migrating processes, it has to be
guaranteed that they never go backward. In an ideal case, the behavior of
these clocks should be the same as for a case when a whole system is
suspended. All this means that it is required to set CLOCK_MONOTONIC and
CLOCK_BOOTTIME clocks, which can be achieved by adding per-namespace
offsets for clocks.
A time namespace is similar to a pid namespace in the way how it is
created: unshare(CLONE_NEWTIME) system call creates a new time namespace,
but doesn't set it to the current process. Then all children of the process
will be born in the new time namespace, or a process can use the setns()
system call to join a namespace.
This scheme allows setting clock offsets for a namespace, before any
processes appear in it.
All available clone flags have been used, so CLONE_NEWTIME uses the highest
bit of CSIGNAL. It means that it can be used only with the unshare() and
the clone3() system calls.
[ tglx: Adjusted paragraph about clone3() to reality and massaged the
changelog a bit. ]
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://criu.org/Time_namespace
Link: https://lists.openvz.org/pipermail/criu/2018-June/041504.html
Link: https://lore.kernel.org/r/20191112012724.250792-4-dima@arista.com
|
||
Amanieu d'Antras
|
dd499f7a7e
|
clone3: ensure copy_thread_tls is implemented
copy_thread implementations handle CLONE_SETTLS by reading the TLS value from the registers containing the syscall arguments for clone. This doesn't work with clone3 since the TLS value is passed in clone_args instead. Signed-off-by: Amanieu d'Antras <amanieu@gmail.com> Cc: <stable@vger.kernel.org> # 5.3.x Link: https://lore.kernel.org/r/20200102172413.654385-8-amanieu@gmail.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
||
|
Linus Torvalds
|
043cf46825 |
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Ingo Molnar:
"The main changes in the timer code in this cycle were:
- Clockevent updates:
- timer-of framework cleanups. (Geert Uytterhoeven)
- Use timer-of for the renesas-ostm and the device name to prevent
name collision in case of multiple timers. (Geert Uytterhoeven)
- Check if there is an error after calling of_clk_get in asm9260
(Chuhong Yuan)
- ABI fix: Zero out high order bits of nanoseconds on compat
syscalls. This got broken a year ago, with apparently no side
effects so far.
Since the kernel would use random data otherwise I don't think we'd
have other options but to fix the bug, even if there was a side
effect to applications (Dmitry Safonov)
- Optimize ns_to_timespec64() on 32-bit systems: move away from
div_s64_rem() which can be slow, to div_u64_rem() which is faster
(Arnd Bergmann)
- Annotate KCSAN-reported false positive data races in
hrtimer_is_queued() users by moving timer->state handling over to
the READ_ONCE()/WRITE_ONCE() APIs. This documents these accesses
(Eric Dumazet)
- Misc cleanups and small fixes"
[ I undid the "ABI fix" and updated the comments instead. The reason
there were apparently no side effects is that the fix was a no-op.
The updated comment is to say _why_ it was a no-op. - Linus ]
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Zero the upper 32-bits in __kernel_timespec on 32-bit
time: Rename tsk->real_start_time to ->start_boottime
hrtimer: Remove the comment about not used HRTIMER_SOFTIRQ
time: Fix spelling mistake in comment
time: Optimize ns_to_timespec64()
hrtimer: Annotate lockless access to timer->state
clocksource/drivers/asm9260: Add a check for of_clk_get
clocksource/drivers/renesas-ostm: Use unique device name instead of ostm
clocksource/drivers/renesas-ostm: Convert to timer_of
clocksource/drivers/timer-of: Use unique device name instead of timer
clocksource/drivers/timer-of: Convert last full_name to %pOF
|
||
Daniel Axtens
|
eafb149ed7 |
fork: support VMAP_STACK with KASAN_VMALLOC
Supporting VMAP_STACK with KASAN_VMALLOC is straightforward: - clear the shadow region of vmapped stacks when swapping them in - tweak Kconfig to allow VMAP_STACK to be turned on with KASAN Link: http://lkml.kernel.org/r/20191031093909.9228-4-dja@axtens.net Signed-off-by: Daniel Axtens <dja@axtens.net> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Linus Torvalds
|
aa32f11691 |
hmm related patches for 5.5
This is another round of bug fixing and cleanup. This time the focus is on
the driver pattern to use mmu notifiers to monitor a VA range. This code
is lifted out of many drivers and hmm_mirror directly into the
mmu_notifier core and written using the best ideas from all the driver
implementations.
This removes many bugs from the drivers and has a very pleasing
diffstat. More drivers can still be converted, but that is for another
cycle.
- A shared branch with RDMA reworking the RDMA ODP implementation
- New mmu_interval_notifier API. This is focused on the use case of
monitoring a VA and simplifies the process for drivers
- A common seq-count locking scheme built into the mmu_interval_notifier
API usable by drivers that call get_user_pages() or hmm_range_fault()
with the VA range
- Conversion of mlx5 ODP, hfi1, radeon, nouveau, AMD GPU, and Xen GntDev
drivers to the new API. This deletes a lot of wonky driver code.
- Two improvements for hmm_range_fault(), from testing done by Ralph
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Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma
Pull hmm updates from Jason Gunthorpe:
"This is another round of bug fixing and cleanup. This time the focus
is on the driver pattern to use mmu notifiers to monitor a VA range.
This code is lifted out of many drivers and hmm_mirror directly into
the mmu_notifier core and written using the best ideas from all the
driver implementations.
This removes many bugs from the drivers and has a very pleasing
diffstat. More drivers can still be converted, but that is for another
cycle.
- A shared branch with RDMA reworking the RDMA ODP implementation
- New mmu_interval_notifier API. This is focused on the use case of
monitoring a VA and simplifies the process for drivers
- A common seq-count locking scheme built into the
mmu_interval_notifier API usable by drivers that call
get_user_pages() or hmm_range_fault() with the VA range
- Conversion of mlx5 ODP, hfi1, radeon, nouveau, AMD GPU, and Xen
GntDev drivers to the new API. This deletes a lot of wonky driver
code.
- Two improvements for hmm_range_fault(), from testing done by Ralph"
* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
mm/hmm: remove hmm_range_dma_map and hmm_range_dma_unmap
mm/hmm: make full use of walk_page_range()
xen/gntdev: use mmu_interval_notifier_insert
mm/hmm: remove hmm_mirror and related
drm/amdgpu: Use mmu_interval_notifier instead of hmm_mirror
drm/amdgpu: Use mmu_interval_insert instead of hmm_mirror
drm/amdgpu: Call find_vma under mmap_sem
nouveau: use mmu_interval_notifier instead of hmm_mirror
nouveau: use mmu_notifier directly for invalidate_range_start
drm/radeon: use mmu_interval_notifier_insert
RDMA/hfi1: Use mmu_interval_notifier_insert for user_exp_rcv
RDMA/odp: Use mmu_interval_notifier_insert()
mm/hmm: define the pre-processor related parts of hmm.h even if disabled
mm/hmm: allow hmm_range to be used with a mmu_interval_notifier or hmm_mirror
mm/mmu_notifier: add an interval tree notifier
mm/mmu_notifier: define the header pre-processor parts even if disabled
mm/hmm: allow snapshot of the special zero page
|
||
|
Linus Torvalds
|
168829ad09 |
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"The main changes in this cycle were:
- A comprehensive rewrite of the robust/PI futex code's exit handling
to fix various exit races. (Thomas Gleixner et al)
- Rework the generic REFCOUNT_FULL implementation using
atomic_fetch_* operations so that the performance impact of the
cmpxchg() loops is mitigated for common refcount operations.
With these performance improvements the generic implementation of
refcount_t should be good enough for everybody - and this got
confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and
REFCOUNT_FULL entirely, leaving the generic implementation enabled
unconditionally. (Will Deacon)
- Other misc changes, fixes, cleanups"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
lkdtm: Remove references to CONFIG_REFCOUNT_FULL
locking/refcount: Remove unused 'refcount_error_report()' function
locking/refcount: Consolidate implementations of refcount_t
locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions
locking/refcount: Move saturation warnings out of line
locking/refcount: Improve performance of generic REFCOUNT_FULL code
locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header
locking/refcount: Remove unused refcount_*_checked() variants
locking/refcount: Ensure integer operands are treated as signed
locking/refcount: Define constants for saturation and max refcount values
futex: Prevent exit livelock
futex: Provide distinct return value when owner is exiting
futex: Add mutex around futex exit
futex: Provide state handling for exec() as well
futex: Sanitize exit state handling
futex: Mark the begin of futex exit explicitly
futex: Set task::futex_state to DEAD right after handling futex exit
futex: Split futex_mm_release() for exit/exec
exit/exec: Seperate mm_release()
futex: Replace PF_EXITPIDONE with a state
...
|
||
|
Linus Torvalds
|
0acefef584 |
threads-v5.5
-----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCXdfjBwAKCRCRxhvAZXjc onCBAP47WZ/ie7yjoDWhOI1QB7II3NGSzToakxpgJaWoB+NjTwEA7PGrSYVEbPrf pUhiEaEJ29t+cWUxX3+yDO+k7SA6BAY= =Ra58 -----END PGP SIGNATURE----- Merge tag 'threads-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull thread management updates from Christian Brauner: - A pidfd's fdinfo file currently contains the field "Pid:\t<pid>" where <pid> is the pid of the process in the pid namespace of the procfs instance the fdinfo file for the pidfd was opened in. The fdinfo file has now gained a new "NSpid:\t<ns-pid1>[\t<ns-pid2>[...]]" field which lists the pids of the process in all child pid namespaces provided the pid namespace of the procfs instance it is looked up under has an ancestoral relationship with the pid namespace of the process. If it does not 0 will be shown and no further pid namespaces will be listed. Tests included. (Christian Kellner) - If the process the pidfd references has already exited, print -1 for the Pid and NSpid fields in the pidfd's fdinfo file. Tests included. (me) - Add CLONE_CLEAR_SIGHAND. This lets callers clear all signal handler that are not SIG_DFL or SIG_IGN at process creation time. This originated as a feature request from glibc to improve performance and elimate races in their posix_spawn() implementation. Tests included. (me) - Add support for choosing a specific pid for a process with clone3(). This is the feature which was part of the thread update for v5.4 but after a discussion at LPC in Lisbon we decided to delay it for one more cycle in order to make the interface more generic. This has now done. It is now possible to choose a specific pid in a whole pid namespaces (sub)hierarchy instead of just one pid namespace. In order to choose a specific pid the caller must have CAP_SYS_ADMIN in all owning user namespaces of the target pid namespaces. Tests included. (Adrian Reber) - Test improvements and extensions. (Andrei Vagin, me) * tag 'threads-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: selftests/clone3: skip if clone3() is ENOSYS selftests/clone3: check that all pids are released on error paths selftests/clone3: report a correct number of fails selftests/clone3: flush stdout and stderr before clone3() and _exit() selftests: add tests for clone3() with *set_tid fork: extend clone3() to support setting a PID selftests: add tests for clone3() tests: test CLONE_CLEAR_SIGHAND clone3: add CLONE_CLEAR_SIGHAND pid: use pid_has_task() in pidfd_open() exit: use pid_has_task() in do_wait() pid: use pid_has_task() in __change_pid() test: verify fdinfo for pidfd of reaped process pidfd: check pid has attached task in fdinfo pidfd: add tests for NSpid info in fdinfo pidfd: add NSpid entries to fdinfo |
||
Ingo Molnar
|
83bae01182 |
Merge branch 'timers/urgent' into timers/core, to pick up fix
Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Jason Gunthorpe
|
107e899874 |
mm/hmm: define the pre-processor related parts of hmm.h even if disabled
Only the function calls are stubbed out with static inlines that always fail. This is the standard way to write a header for an optional component and makes it easier for drivers that only optionally need HMM_MIRROR. Link: https://lore.kernel.org/r/20191112202231.3856-5-jgg@ziepe.ca Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> |
||
Luc Van Oostenryck
|
9e77716a75 |
fork: fix pidfd_poll()'s return type
pidfd_poll() is defined as returning 'unsigned int' but the
.poll method is declared as returning '__poll_t', a bitwise type.
Fix this by using the proper return type and using the EPOLL
constants instead of the POLL ones, as required for __poll_t.
Fixes:
|
||
Thomas Gleixner
|
150d71584b |
futex: Split futex_mm_release() for exit/exec
To allow separate handling of the futex exit state in the futex exit code for exit and exec, split futex_mm_release() into two functions and invoke them from the corresponding exit/exec_mm_release() callsites. Preparatory only, no functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.332094221@linutronix.de |
||
|
Thomas Gleixner
|
4610ba7ad8 |
exit/exec: Seperate mm_release()
mm_release() contains the futex exit handling. mm_release() is called from do_exit()->exit_mm() and from exec()->exec_mm(). In the exit_mm() case PF_EXITING and the futex state is updated. In the exec_mm() case these states are not touched. As the futex exit code needs further protections against exit races, this needs to be split into two functions. Preparatory only, no functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.240518241@linutronix.de |
||
|
Thomas Gleixner
|
ba31c1a485 |
futex: Move futex exit handling into futex code
The futex exit handling is #ifdeffed into mm_release() which is not pretty to begin with. But upcoming changes to address futex exit races need to add more functionality to this exit code. Split it out into a function, move it into futex code and make the various futex exit functions static. Preparatory only and no functional change. Folded build fix from Borislav. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.049705556@linutronix.de |
||
Adrian Reber
|
49cb2fc42c |
fork: extend clone3() to support setting a PID
The main motivation to add set_tid to clone3() is CRIU.
To restore a process with the same PID/TID CRIU currently uses
/proc/sys/kernel/ns_last_pid. It writes the desired (PID - 1) to
ns_last_pid and then (quickly) does a clone(). This works most of the
time, but it is racy. It is also slow as it requires multiple syscalls.
Extending clone3() to support *set_tid makes it possible restore a
process using CRIU without accessing /proc/sys/kernel/ns_last_pid and
race free (as long as the desired PID/TID is available).
This clone3() extension places the same restrictions (CAP_SYS_ADMIN)
on clone3() with *set_tid as they are currently in place for ns_last_pid.
The original version of this change was using a single value for
set_tid. At the 2019 LPC, after presenting set_tid, it was, however,
decided to change set_tid to an array to enable setting the PID of a
process in multiple PID namespaces at the same time. If a process is
created in a PID namespace it is possible to influence the PID inside
and outside of the PID namespace. Details also in the corresponding
selftest.
To create a process with the following PIDs:
PID NS level Requested PID
0 (host) 31496
1 42
2 1
For that example the two newly introduced parameters to struct
clone_args (set_tid and set_tid_size) would need to be:
set_tid[0] = 1;
set_tid[1] = 42;
set_tid[2] = 31496;
set_tid_size = 3;
If only the PIDs of the two innermost nested PID namespaces should be
defined it would look like this:
set_tid[0] = 1;
set_tid[1] = 42;
set_tid_size = 2;
The PID of the newly created process would then be the next available
free PID in the PID namespace level 0 (host) and 42 in the PID namespace
at level 1 and the PID of the process in the innermost PID namespace
would be 1.
The set_tid array is used to specify the PID of a process starting
from the innermost nested PID namespaces up to set_tid_size PID namespaces.
set_tid_size cannot be larger then the current PID namespace level.
Signed-off-by: Adrian Reber <areber@redhat.com>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Acked-by: Andrei Vagin <avagin@gmail.com>
Link: https://lore.kernel.org/r/20191115123621.142252-1-areber@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
|
||
Peter Zijlstra
|
cf25e24db6 |
time: Rename tsk->real_start_time to ->start_boottime
Since it stores CLOCK_BOOTTIME, not, as the name suggests, CLOCK_REALTIME, let's rename ->real_start_time to ->start_bootime. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Christian Brauner
|
fa729c4df5
|
clone3: validate stack arguments
Validate the stack arguments and setup the stack depening on whether or not
it is growing down or up.
Legacy clone() required userspace to know in which direction the stack is
growing and pass down the stack pointer appropriately. To make things more
confusing microblaze uses a variant of the clone() syscall selected by
CONFIG_CLONE_BACKWARDS3 that takes an additional stack_size argument.
IA64 has a separate clone2() syscall which also takes an additional
stack_size argument. Finally, parisc has a stack that is growing upwards.
Userspace therefore has a lot nasty code like the following:
#define __STACK_SIZE (8 * 1024 * 1024)
pid_t sys_clone(int (*fn)(void *), void *arg, int flags, int *pidfd)
{
pid_t ret;
void *stack;
stack = malloc(__STACK_SIZE);
if (!stack)
return -ENOMEM;
#ifdef __ia64__
ret = __clone2(fn, stack, __STACK_SIZE, flags | SIGCHLD, arg, pidfd);
#elif defined(__parisc__) /* stack grows up */
ret = clone(fn, stack, flags | SIGCHLD, arg, pidfd);
#else
ret = clone(fn, stack + __STACK_SIZE, flags | SIGCHLD, arg, pidfd);
#endif
return ret;
}
or even crazier variants such as [3].
With clone3() we have the ability to validate the stack. We can check that
when stack_size is passed, the stack pointer is valid and the other way
around. We can also check that the memory area userspace gave us is fine to
use via access_ok(). Furthermore, we probably should not require
userspace to know in which direction the stack is growing. It is easy
for us to do this in the kernel and I couldn't find the original
reasoning behind exposing this detail to userspace.
/* Intentional user visible API change */
clone3() was released with 5.3. Currently, it is not documented and very
unclear to userspace how the stack and stack_size argument have to be
passed. After talking to glibc folks we concluded that trying to change
clone3() to setup the stack instead of requiring userspace to do this is
the right course of action.
Note, that this is an explicit change in user visible behavior we introduce
with this patch. If it breaks someone's use-case we will revert! (And then
e.g. place the new behavior under an appropriate flag.)
Breaking someone's use-case is very unlikely though. First, neither glibc
nor musl currently expose a wrapper for clone3(). Second, there is no real
motivation for anyone to use clone3() directly since it does not provide
features that legacy clone doesn't. New features for clone3() will first
happen in v5.5 which is why v5.4 is still a good time to try and make that
change now and backport it to v5.3. Searches on [4] did not reveal any
packages calling clone3().
[1]: https://lore.kernel.org/r/CAG48ez3q=BeNcuVTKBN79kJui4vC6nw0Bfq6xc-i0neheT17TA@mail.gmail.com
[2]: https://lore.kernel.org/r/20191028172143.4vnnjpdljfnexaq5@wittgenstein
[3]:
|
||
|
Christian Brauner
|
b612e5df45
|
clone3: add CLONE_CLEAR_SIGHAND
Reset all signal handlers of the child not set to SIG_IGN to SIG_DFL. Mutually exclusive with CLONE_SIGHAND to not disturb other thread's signal handler. In the spirit of closer cooperation between glibc developers and kernel developers (cf. [2]) this patchset came out of a discussion on the glibc mailing list for improving posix_spawn() (cf. [1], [3], [4]). Kernel support for this feature has been explicitly requested by glibc and I see no reason not to help them with this. The child helper process on Linux posix_spawn must ensure that no signal handlers are enabled, so the signal disposition must be either SIG_DFL or SIG_IGN. However, it requires a sigprocmask to obtain the current signal mask and at least _NSIG sigaction calls to reset the signal handlers for each posix_spawn call or complex state tracking that might lead to data corruption in glibc. Adding this flags lets glibc avoid these problems. [1]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00149.html [3]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00158.html [4]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00160.html [2]: https://lwn.net/Articles/799331/ '[...] by asking for better cooperation with the C-library projects in general. They should be copied on patches containing ABI changes, for example. I noted that there are often times where C-library developers wish the kernel community had done things differently; how could those be avoided in the future? Members of the audience suggested that more glibc developers should perhaps join the linux-api list. The other suggestion was to "copy Florian on everything".' Cc: Florian Weimer <fweimer@redhat.com> Cc: libc-alpha@sourceware.org Cc: linux-api@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20191014104538.3096-1-christian.brauner@ubuntu.com |
||
|
Christian Brauner
|
3d6d8da48d
|
pidfd: check pid has attached task in fdinfo
Currently, when a task is dead we still print the pid it used to use in the fdinfo files of its pidfds. This doesn't make much sense since the pid may have already been reused. So verify that the task is still alive by introducing the pid_has_task() helper which will be used by other callers in follow-up patches. If the task is not alive anymore, we will print -1. This allows us to differentiate between a task not being present in a given pid namespace - in which case we already print 0 - and a task having been reaped. Note that this uses PIDTYPE_PID for the check. Technically, we could've checked PIDTYPE_TGID since pidfds currently only refer to thread-group leaders but if they won't anymore in the future then this check becomes problematic without it being immediately obvious to non-experts imho. If a thread is created via clone(CLONE_THREAD) than struct pid has a single non-empty list pid->tasks[PIDTYPE_PID] and this pid can't be used as a PIDTYPE_TGID meaning pid->tasks[PIDTYPE_TGID] will return NULL even though the thread-group leader might still be very much alive. So checking PIDTYPE_PID is fine and is easier to maintain should we ever allow pidfds to refer to threads. Cc: Jann Horn <jannh@google.com> Cc: Christian Kellner <christian@kellner.me> Cc: linux-api@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20191017101832.5985-1-christian.brauner@ubuntu.com |
||
Christian Kellner
|
15d42eb26b |
pidfd: add NSpid entries to fdinfo
Currently, the fdinfo file contains the Pid field which shows the pid a given pidfd refers to in the pid namespace of the procfs instance. If pid namespaces are configured, also show an NSpid field for easy retrieval of the pid in all descendant pid namespaces. If the pid namespace of the process is not a descendant of the pid namespace of the procfs instance 0 will be shown as its first NSpid entry and no other entries will be shown. Add a block comment to pidfd_show_fdinfo with a detailed explanation of Pid and NSpid fields. Co-developed-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Christian Kellner <christian@kellner.me> Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20191014162034.2185-1-ckellner@redhat.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
||
Michal Hocko
|
b0f53dbc4b |
kernel/sysctl.c: do not override max_threads provided by userspace
Partially revert |
||
|
Linus Torvalds
|
e524d16e7e |
copy-struct-from-user-v5.4-rc2
-----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCXZZIgQAKCRCRxhvAZXjc orNOAP98B2nmoxvq8d5Z6PhoyTBC5NIUuJ5h2YMwcX/hAaj5uQEA58NTKtPmOPDR 2ffUFFerGZ2+brlHgACa0ZKdH27TjAA= =QryD -----END PGP SIGNATURE----- Merge tag 'copy-struct-from-user-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull copy_struct_from_user() helper from Christian Brauner: "This contains the copy_struct_from_user() helper which got split out from the openat2() patchset. It is a generic interface designed to copy a struct from userspace. The helper will be especially useful for structs versioned by size of which we have quite a few. This allows for backwards compatibility, i.e. an extended struct can be passed to an older kernel, or a legacy struct can be passed to a newer kernel. For the first case (extended struct, older kernel) the new fields in an extended struct can be set to zero and the struct safely passed to an older kernel. The most obvious benefit is that this helper lets us get rid of duplicate code present in at least sched_setattr(), perf_event_open(), and clone3(). More importantly it will also help to ensure that users implementing versioning-by-size end up with the same core semantics. This point is especially crucial since we have at least one case where versioning-by-size is used but with slighly different semantics: sched_setattr(), perf_event_open(), and clone3() all do do similar checks to copy_struct_from_user() while rt_sigprocmask(2) always rejects differently-sized struct arguments. With this pull request we also switch over sched_setattr(), perf_event_open(), and clone3() to use the new helper" * tag 'copy-struct-from-user-v5.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: usercopy: Add parentheses around assignment in test_copy_struct_from_user perf_event_open: switch to copy_struct_from_user() sched_setattr: switch to copy_struct_from_user() clone3: switch to copy_struct_from_user() lib: introduce copy_struct_from_user() helper |
||
|
Christian Brauner
|
501bd0166e
|
fork: add kernel-doc for clone3
Add kernel-doc for the clone3() syscall. Link: https://lore.kernel.org/r/20191001114701.24661-2-christian.brauner@ubuntu.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
||
Aleksa Sarai
|
f14c234b4b |
clone3: switch to copy_struct_from_user()
Switch clone3() syscall from it's own copying struct clone_args from userspace to the new dedicated copy_struct_from_user() helper. The change is very straightforward, and helps unify the syscall interface for struct-from-userspace syscalls. Additionally, explicitly define CLONE_ARGS_SIZE_VER0 to match the other users of the struct-extension pattern. Signed-off-by: Aleksa Sarai <cyphar@cyphar.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com> [christian.brauner@ubuntu.com: improve commit message] Link: https://lore.kernel.org/r/20191001011055.19283-3-cyphar@cyphar.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> |
||
|
Linus Torvalds
|
9c5efe9ae7 |
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar: - Apply a number of membarrier related fixes and cleanups, which fixes a use-after-free race in the membarrier code - Introduce proper RCU protection for tasks on the runqueue - to get rid of the subtle task_rcu_dereference() interface that was easy to get wrong - Misc fixes, but also an EAS speedup * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Avoid redundant EAS calculation sched/core: Remove double update_max_interval() call on CPU startup sched/core: Fix preempt_schedule() interrupt return comment sched/fair: Fix -Wunused-but-set-variable warnings sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr() sched/membarrier: Return -ENOMEM to userspace on memory allocation failure sched/membarrier: Skip IPIs when mm->mm_users == 1 selftests, sched/membarrier: Add multi-threaded test sched/membarrier: Fix p->mm->membarrier_state racy load sched/membarrier: Call sync_core only before usermode for same mm sched/membarrier: Remove redundant check sched/membarrier: Fix private expedited registration check tasks, sched/core: RCUify the assignment of rq->curr tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue tasks: Add a count of task RCU users sched/core: Convert vcpu_is_preempted() from macro to an inline function sched/fair: Remove unused cfs_rq_clock_task() function |
||
Sai Praneeth Prakhya
|
8495f7e673 |
fork: improve error message for corrupted page tables
When a user process exits, the kernel cleans up the mm_struct of the user process and during cleanup, check_mm() checks the page tables of the user process for corruption (E.g: unexpected page flags set/cleared). For corrupted page tables, the error message printed by check_mm() isn't very clear as it prints the loop index instead of page table type (E.g: Resident file mapping pages vs Resident shared memory pages). The loop index in check_mm() is used to index rss_stat[] which represents individual memory type stats. Hence, instead of printing index, print memory type, thereby improving error message. Without patch: -------------- [ 204.836425] mm/pgtable-generic.c:29: bad p4d 0000000089eb4e92(800000025f941467) [ 204.836544] BUG: Bad rss-counter state mm:00000000f75895ea idx:0 val:2 [ 204.836615] BUG: Bad rss-counter state mm:00000000f75895ea idx:1 val:5 [ 204.836685] BUG: non-zero pgtables_bytes on freeing mm: 20480 With patch: ----------- [ 69.815453] mm/pgtable-generic.c:29: bad p4d 0000000084653642(800000025ca37467) [ 69.815872] BUG: Bad rss-counter state mm:00000000014a6c03 type:MM_FILEPAGES val:2 [ 69.815962] BUG: Bad rss-counter state mm:00000000014a6c03 type:MM_ANONPAGES val:5 [ 69.816050] BUG: non-zero pgtables_bytes on freeing mm: 20480 Also, change print function (from printk(KERN_ALERT, ..) to pr_alert()) so that it matches the other print statement. Link: http://lkml.kernel.org/r/da75b5153f617f4c5739c08ee6ebeb3d19db0fbc.1565123758.git.sai.praneeth.prakhya@intel.com Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Suggested-by: Dave Hansen <dave.hansen@intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Dave Hansen <dave.hansen@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
|
Eric W. Biederman
|
0ff7b2cfba |
tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue
In the ordinary case today the RCU grace period for a task_struct is triggered when another process wait's for it's zombine and causes the kernel to call release_task(). As the waiting task has to receive a signal and then act upon it before this happens, typically this will occur after the original task as been removed from the runqueue. Unfortunaty in some cases such as self reaping tasks it can be shown that release_task() will be called starting the grace period for task_struct long before the task leaves the runqueue. Therefore use put_task_struct_rcu_user() in finish_task_switch() to guarantee that the there is a RCU lifetime after the task leaves the runqueue. Besides the change in the start of the RCU grace period for the task_struct this change may cause perf_event_delayed_put and trace_sched_process_free. The function perf_event_delayed_put boils down to just a WARN_ON for cases that I assume never show happen. So I don't see any problem with delaying it. The function trace_sched_process_free is a trace point and thus visible to user space. Occassionally userspace has the strangest dependencies so this has a miniscule chance of causing a regression. This change only changes the timing of when the tracepoint is called. The change in timing arguably gives userspace a more accurate picture of what is going on. So I don't expect there to be a regression. In the case where a task self reaps we are pretty much guaranteed that the RCU grace period is delayed. So we should get quite a bit of coverage in of this worst case for the change in a normal threaded workload. So I expect any issues to turn up quickly or not at all. I have lightly tested this change and everything appears to work fine. Inspired-by: Linus Torvalds <torvalds@linux-foundation.org> Inspired-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87r24jdpl5.fsf_-_@x220.int.ebiederm.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Eric W. Biederman
|
3fbd7ee285 |
tasks: Add a count of task RCU users
Add a count of the number of RCU users (currently 1) of the task struct so that we can later add the scheduler case and get rid of the very subtle task_rcu_dereference(), and just use rcu_dereference(). As suggested by Oleg have the count overlap rcu_head so that no additional space in task_struct is required. Inspired-by: Linus Torvalds <torvalds@linux-foundation.org> Inspired-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87woebdplt.fsf_-_@x220.int.ebiederm.org Signed-off-by: Ingo Molnar <mingo@kernel.org> |
||
|
Linus Torvalds
|
84da111de0 |
hmm related patches for 5.4
This is more cleanup and consolidation of the hmm APIs and the very
strongly related mmu_notifier interfaces. Many places across the tree
using these interfaces are touched in the process. Beyond that a cleanup
to the page walker API and a few memremap related changes round out the
series:
- General improvement of hmm_range_fault() and related APIs, more
documentation, bug fixes from testing, API simplification &
consolidation, and unused API removal
- Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE, and
make them internal kconfig selects
- Hoist a lot of code related to mmu notifier attachment out of drivers by
using a refcount get/put attachment idiom and remove the convoluted
mmu_notifier_unregister_no_release() and related APIs.
- General API improvement for the migrate_vma API and revision of its only
user in nouveau
- Annotate mmu_notifiers with lockdep and sleeping region debugging
Two series unrelated to HMM or mmu_notifiers came along due to
dependencies:
- Allow pagemap's memremap_pages family of APIs to work without providing
a struct device
- Make walk_page_range() and related use a constant structure for function
pointers
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Merge tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma
Pull hmm updates from Jason Gunthorpe:
"This is more cleanup and consolidation of the hmm APIs and the very
strongly related mmu_notifier interfaces. Many places across the tree
using these interfaces are touched in the process. Beyond that a
cleanup to the page walker API and a few memremap related changes
round out the series:
- General improvement of hmm_range_fault() and related APIs, more
documentation, bug fixes from testing, API simplification &
consolidation, and unused API removal
- Simplify the hmm related kconfigs to HMM_MIRROR and DEVICE_PRIVATE,
and make them internal kconfig selects
- Hoist a lot of code related to mmu notifier attachment out of
drivers by using a refcount get/put attachment idiom and remove the
convoluted mmu_notifier_unregister_no_release() and related APIs.
- General API improvement for the migrate_vma API and revision of its
only user in nouveau
- Annotate mmu_notifiers with lockdep and sleeping region debugging
Two series unrelated to HMM or mmu_notifiers came along due to
dependencies:
- Allow pagemap's memremap_pages family of APIs to work without
providing a struct device
- Make walk_page_range() and related use a constant structure for
function pointers"
* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (75 commits)
libnvdimm: Enable unit test infrastructure compile checks
mm, notifier: Catch sleeping/blocking for !blockable
kernel.h: Add non_block_start/end()
drm/radeon: guard against calling an unpaired radeon_mn_unregister()
csky: add missing brackets in a macro for tlb.h
pagewalk: use lockdep_assert_held for locking validation
pagewalk: separate function pointers from iterator data
mm: split out a new pagewalk.h header from mm.h
mm/mmu_notifiers: annotate with might_sleep()
mm/mmu_notifiers: prime lockdep
mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end
mm/mmu_notifiers: remove the __mmu_notifier_invalidate_range_start/end exports
mm/hmm: hmm_range_fault() infinite loop
mm/hmm: hmm_range_fault() NULL pointer bug
mm/hmm: fix hmm_range_fault()'s handling of swapped out pages
mm/mmu_notifiers: remove unregister_no_release
RDMA/odp: remove ib_ucontext from ib_umem
RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm'
RDMA/mlx5: Use odp instead of mr->umem in pagefault_mr
RDMA/mlx5: Use ib_umem_start instead of umem.address
...
|
||
|
Linus Torvalds
|
7f2444d38f |
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core timer updates from Thomas Gleixner:
"Timers and timekeeping updates:
- A large overhaul of the posix CPU timer code which is a preparation
for moving the CPU timer expiry out into task work so it can be
properly accounted on the task/process.
An update to the bogus permission checks will come later during the
merge window as feedback was not complete before heading of for
travel.
- Switch the timerqueue code to use cached rbtrees and get rid of the
homebrewn caching of the leftmost node.
- Consolidate hrtimer_init() + hrtimer_init_sleeper() calls into a
single function
- Implement the separation of hrtimers to be forced to expire in hard
interrupt context even when PREEMPT_RT is enabled and mark the
affected timers accordingly.
- Implement a mechanism for hrtimers and the timer wheel to protect
RT against priority inversion and live lock issues when a (hr)timer
which should be canceled is currently executing the callback.
Instead of infinitely spinning, the task which tries to cancel the
timer blocks on a per cpu base expiry lock which is held and
released by the (hr)timer expiry code.
- Enable the Hyper-V TSC page based sched_clock for Hyper-V guests
resulting in faster access to timekeeping functions.
- Updates to various clocksource/clockevent drivers and their device
tree bindings.
- The usual small improvements all over the place"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
posix-cpu-timers: Fix permission check regression
posix-cpu-timers: Always clear head pointer on dequeue
hrtimer: Add a missing bracket and hide `migration_base' on !SMP
posix-cpu-timers: Make expiry_active check actually work correctly
posix-timers: Unbreak CONFIG_POSIX_TIMERS=n build
tick: Mark sched_timer to expire in hard interrupt context
hrtimer: Add kernel doc annotation for HRTIMER_MODE_HARD
x86/hyperv: Hide pv_ops access for CONFIG_PARAVIRT=n
posix-cpu-timers: Utilize timerqueue for storage
posix-cpu-timers: Move state tracking to struct posix_cputimers
posix-cpu-timers: Deduplicate rlimit handling
posix-cpu-timers: Remove pointless comparisons
posix-cpu-timers: Get rid of 64bit divisions
posix-cpu-timers: Consolidate timer expiry further
posix-cpu-timers: Get rid of zero checks
rlimit: Rewrite non-sensical RLIMIT_CPU comment
posix-cpu-timers: Respect INFINITY for hard RTTIME limit
posix-cpu-timers: Switch thread group sampling to array
posix-cpu-timers: Restructure expiry array
posix-cpu-timers: Remove cputime_expires
...
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Linus Torvalds
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76f0f227cf |
ia64 for v5.4 - big change here is removal of support for SGI Altix
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Linus Torvalds
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c17112a5c4 |
core-process-v5.4
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Merge tag 'core-process-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull pidfd/waitid updates from Christian Brauner:
"This contains two features and various tests.
First, it adds support for waiting on process through pidfds by adding
the P_PIDFD type to the waitid() syscall. This completes the basic
functionality of the pidfd api (cf. [1]). In the meantime we also have
a new adition to the userspace projects that make use of the pidfd
api. The qt project was nice enough to send a mail pointing out that
they have a pr up to switch to the pidfd api (cf. [2]).
Second, this tag contains an extension to the waitid() syscall to make
it possible to wait on the current process group in a race free manner
(even though the actual problem is very unlikely) by specifing 0
together with the P_PGID type. This extension traces back to a
discussion on the glibc development mailing list.
There are also a range of tests for the features above. Additionally,
the test-suite which detected the pidfd-polling race we fixed in [3]
is included in this tag"
[1] https://lwn.net/Articles/794707/
[2] https://codereview.qt-project.org/c/qt/qtbase/+/108456
[3] commit
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Eugene Syromiatnikov
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a0eb9abd8a
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fork: block invalid exit signals with clone3()
Previously, higher 32 bits of exit_signal fields were lost when copied
to the kernel args structure (that uses int as a type for the respective
field). Moreover, as Oleg has noted, exit_signal is used unchecked, so
it has to be checked for sanity before use; for the legacy syscalls,
applying CSIGNAL mask guarantees that it is at least non-negative;
however, there's no such thing is done in clone3() code path, and that
can break at least thread_group_leader.
This commit adds a check to copy_clone_args_from_user() to verify that
the exit signal is limited by CSIGNAL as with legacy clone() and that
the signal is valid. With this we don't get the legacy clone behavior
were an invalid signal could be handed down and would only be detected
and ignored in do_notify_parent(). Users of clone3() will now get a
proper error when they pass an invalid exit signal. Note, that this is
not user-visible behavior since no kernel with clone3() has been
released yet.
The following program will cause a splat on a non-fixed clone3() version
and will fail correctly on a fixed version:
#define _GNU_SOURCE
#include <linux/sched.h>
#include <linux/types.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
pid_t pid = -1;
struct clone_args args = {0};
args.exit_signal = -1;
pid = syscall(__NR_clone3, &args, sizeof(struct clone_args));
if (pid < 0)
exit(EXIT_FAILURE);
if (pid == 0)
exit(EXIT_SUCCESS);
wait(NULL);
exit(EXIT_SUCCESS);
}
Fixes:
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