The page cache and most shrinkable slab caches hold data that has been
read from disk, but there are some caches that only cache CPU work, such
as the dentry and inode caches of procfs and sysfs, as well as the subset
of radix tree nodes that track non-resident page cache.
Currently, all these are shrunk at the same rate: using DEFAULT_SEEKS for
the shrinker's seeks setting tells the reclaim algorithm that for every
two page cache pages scanned it should scan one slab object.
This is a bogus setting. A virtual inode that required no IO to create is
not twice as valuable as a page cache page; shadow cache entries with
eviction distances beyond the size of memory aren't either.
In most cases, the behavior in practice is still fine. Such virtual
caches don't tend to grow and assert themselves aggressively, and usually
get picked up before they cause problems. But there are scenarios where
that's not true.
Our database workloads suffer from two of those. For one, their file
workingset is several times bigger than available memory, which has the
kernel aggressively create shadow page cache entries for the non-resident
parts of it. The workingset code does tell the VM that most of these are
expendable, but the VM ends up balancing them 2:1 to cache pages as per
the seeks setting. This is a huge waste of memory.
These workloads also deal with tens of thousands of open files and use
/proc for introspection, which ends up growing the proc_inode_cache to
absurdly large sizes - again at the cost of valuable cache space, which
isn't a reasonable trade-off, given that proc inodes can be re-created
without involving the disk.
This patch implements a "zero-seek" setting for shrinkers that results in
a target ratio of 0:1 between their objects and IO-backed caches. This
allows such virtual caches to grow when memory is available (they do
cache/avoid CPU work after all), but effectively disables them as soon as
IO-backed objects are under pressure.
It then switches the shrinkers for procfs and sysfs metadata, as well as
excess page cache shadow nodes, to the new zero-seek setting.
Link: http://lkml.kernel.org/r/20181009184732.762-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Domas Mituzas <dmituzas@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several definitions of those functions/macros in places that
mess with fixed-point load averages. Provide an official version.
[akpm@linux-foundation.org: fix missed conversion in block/blk-iolatency.c]
Link: http://lkml.kernel.org/r/20180828172258.3185-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vmstat NR_KERNEL_MISC_RECLAIMABLE counter is for kernel non-slab
allocations that can be reclaimed via shrinker. In /proc/meminfo, we can
show the sum of all reclaimable kernel allocations (including slab) as
"KReclaimable". Add the same counter also to per-node meminfo under /sys
With this counter, users will have more complete information about kernel
memory usage. Non-slab reclaimable pages (currently just the ION
allocator) will not be missing from /proc/meminfo, making users wonder
where part of their memory went. More precisely, they already appear in
MemAvailable, but without the new counter, it's not obvious why the value
in MemAvailable doesn't fully correspond with the sum of other counters
participating in it.
Link: http://lkml.kernel.org/r/20180731090649.16028-6-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 mm updates from Ingo Molnar:
"Lots of changes in this cycle:
- Lots of CPA (change page attribute) optimizations and related
cleanups (Thomas Gleixner, Peter Zijstra)
- Make lazy TLB mode even lazier (Rik van Riel)
- Fault handler cleanups and improvements (Dave Hansen)
- kdump, vmcore: Enable kdumping encrypted memory with AMD SME
enabled (Lianbo Jiang)
- Clean up VM layout documentation (Baoquan He, Ingo Molnar)
- ... plus misc other fixes and enhancements"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
x86/stackprotector: Remove the call to boot_init_stack_canary() from cpu_startup_entry()
x86/mm: Kill stray kernel fault handling comment
x86/mm: Do not warn about PCI BIOS W+X mappings
resource: Clean it up a bit
resource: Fix find_next_iomem_res() iteration issue
resource: Include resource end in walk_*() interfaces
x86/kexec: Correct KEXEC_BACKUP_SRC_END off-by-one error
x86/mm: Remove spurious fault pkey check
x86/mm/vsyscall: Consider vsyscall page part of user address space
x86/mm: Add vsyscall address helper
x86/mm: Fix exception table comments
x86/mm: Add clarifying comments for user addr space
x86/mm: Break out user address space handling
x86/mm: Break out kernel address space handling
x86/mm: Clarify hardware vs. software "error_code"
x86/mm/tlb: Make lazy TLB mode lazier
x86/mm/tlb: Add freed_tables element to flush_tlb_info
x86/mm/tlb: Add freed_tables argument to flush_tlb_mm_range
smp,cpumask: introduce on_each_cpu_cond_mask
smp: use __cpumask_set_cpu in on_each_cpu_cond
...
Lianbo reported a build error with a particular 32-bit config, see Link
below for details.
Provide a weak copy_oldmem_page_encrypted() function which architectures
can override, in the same manner other functionality in that file is
supplied.
Reported-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
CC: x86@kernel.org
Link: http://lkml.kernel.org/r/710b9d95-2f70-eadf-c4a1-c3dc80ee4ebb@redhat.com
Currently, you can use /proc/self/task/*/stack to cause a stack walk on
a task you control while it is running on another CPU. That means that
the stack can change under the stack walker. The stack walker does
have guards against going completely off the rails and into random
kernel memory, but it can interpret random data from your kernel stack
as instruction pointers and stack pointers. This can cause exposure of
kernel stack contents to userspace.
Restrict the ability to inspect kernel stacks of arbitrary tasks to root
in order to prevent a local attacker from exploiting racy stack unwinding
to leak kernel task stack contents. See the added comment for a longer
rationale.
There don't seem to be any users of this userspace API that can't
gracefully bail out if reading from the file fails. Therefore, I believe
that this change is unlikely to break things. In the case that this patch
does end up needing a revert, the next-best solution might be to fake a
single-entry stack based on wchan.
Link: http://lkml.kernel.org/r/20180927153316.200286-1-jannh@google.com
Fixes: 2ec220e27f ("proc: add /proc/*/stack")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ken Chen <kenchen@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The 'm' kcore_list item could point to kclist_head, and it is incorrect to
look at m->addr / m->size in this case.
There is no choice but to run through the list of entries for every
address if we did not find any entry in the previous iteration
Reset 'm' to NULL in that case at Omar Sandoval's suggestion.
[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/1536100702-28706-1-git-send-email-asmadeus@codewreck.org
Fixes: bf991c2231 ("proc/kcore: optimize multiple page reads")
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Omar Sandoval <osandov@osandov.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull perf updates from Thomas Gleixner:
"Kernel:
- Improve kallsyms coverage
- Add x86 entry trampolines to kcore
- Fix ARM SPE handling
- Correct PPC event post processing
Tools:
- Make the build system more robust
- Small fixes and enhancements all over the place
- Update kernel ABI header copies
- Preparatory work for converting libtraceevnt to a shared library
- License cleanups"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (100 commits)
tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy'
tools arch x86: Update tools's copy of cpufeatures.h
perf python: Fix pyrf_evlist__read_on_cpu() interface
perf mmap: Store real cpu number in 'struct perf_mmap'
perf tools: Remove ext from struct kmod_path
perf tools: Add gzip_is_compressed function
perf tools: Add lzma_is_compressed function
perf tools: Add is_compressed callback to compressions array
perf tools: Move the temp file processing into decompress_kmodule
perf tools: Use compression id in decompress_kmodule()
perf tools: Store compression id into struct dso
perf tools: Add compression id into 'struct kmod_path'
perf tools: Make is_supported_compression() static
perf tools: Make decompress_to_file() function static
perf tools: Get rid of dso__needs_decompress() call in __open_dso()
perf tools: Get rid of dso__needs_decompress() call in symbol__disassemble()
perf tools: Get rid of dso__needs_decompress() call in read_object_code()
tools lib traceevent: Change to SPDX License format
perf llvm: Allow passing options to llc in addition to clang
perf parser: Improve error message for PMU address filters
...
Without CONFIG_MMU, we get a build warning:
fs/proc/vmcore.c:228:12: error: 'vmcoredd_mmap_dumps' defined but not used [-Werror=unused-function]
static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,
The function is only referenced from an #ifdef'ed caller, so
this uses the same #ifdef around it.
Link: http://lkml.kernel.org/r/20180525213526.2117790-1-arnd@arndb.de
Fixes: 7efe48df8a ("vmcore: append device dumps to vmcore as elf notes")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Ganesh Goudar <ganeshgr@chelsio.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vmcoreinfo information is useful for runtime debugging tools, not just
for crash dumps. A lot of this information can be determined by other
means, but this is much more convenient, and it only adds a page at most
to the file.
Link: http://lkml.kernel.org/r/fddbcd08eed76344863303878b12de1c1e2a04b6.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current code does a full search of the segment list every time for
every page. This is wasteful, since it's almost certain that the next
page will be in the same segment. Instead, check if the previous segment
covers the current page before doing the list search.
Link: http://lkml.kernel.org/r/fd346c11090cf93d867e01b8d73a6567c5ac6361.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the ELF file header, program headers, and note segment are
allocated all at once, in some icky code dating back to 2.3. Programs
tend to read the file header, then the program headers, then the note
segment, all separately, so this is a waste of effort. It's cleaner and
more efficient to handle the three separately.
Link: http://lkml.kernel.org/r/19c92cbad0e11f6103ff3274b2e7a7e51a1eb74b.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we're using an rwsem, we can hold it during the entirety of
read_kcore() and have a common return path. This is preparation for the
next change.
[akpm@linux-foundation.org: fix locking bug reported by Tetsuo Handa]
Link: http://lkml.kernel.org/r/d7cfbc1e8a76616f3b699eaff9df0a2730380534.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's a theoretical race condition that will cause /proc/kcore to miss
a memory hotplug event:
CPU0 CPU1
// hotplug event 1
kcore_need_update = 1
open_kcore() open_kcore()
kcore_update_ram() kcore_update_ram()
// Walk RAM // Walk RAM
__kcore_update_ram() __kcore_update_ram()
kcore_need_update = 0
// hotplug event 2
kcore_need_update = 1
kcore_need_update = 0
Note that CPU1 set up the RAM kcore entries with the state after hotplug
event 1 but cleared the flag for hotplug event 2. The RAM entries will
therefore be stale until there is another hotplug event.
This is an extremely unlikely sequence of events, but the fix makes the
synchronization saner, anyways: we serialize the entire update sequence,
which means that whoever clears the flag will always succeed in replacing
the kcore list.
Link: http://lkml.kernel.org/r/6106c509998779730c12400c1b996425df7d7089.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now we only need kclist_lock from user context and at fs init time, and
the following changes need to sleep while holding the kclist_lock.
Link: http://lkml.kernel.org/r/521ba449ebe921d905177410fee9222d07882f0d.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memory hotplug notifier kcore_callback() only needs kclist_lock to
prevent races with __kcore_update_ram(), but we can easily eliminate that
race by using an atomic xchg() in __kcore_update_ram(). This is
preparation for converting kclist_lock to an rwsem.
Link: http://lkml.kernel.org/r/0a4bc89f4dbde8b5b2ea309f7b4fb6a85fe29df2.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "/proc/kcore improvements", v4.
This series makes a few improvements to /proc/kcore. It fixes a couple of
small issues in v3 but is otherwise the same. Patches 1, 2, and 3 are
prep patches. Patch 4 is a fix/cleanup. Patch 5 is another prep patch.
Patches 6 and 7 are optimizations to ->read(). Patch 8 makes it possible
to enable CRASH_CORE on any architecture, which is needed for patch 9.
Patch 9 adds vmcoreinfo to /proc/kcore.
This patch (of 9):
kclist_add() is only called at init time, so there's no point in grabbing
any locks. We're also going to replace the rwlock with a rwsem, which we
don't want to try grabbing during early boot.
While we're here, mark kclist_add() with __init so that we'll get a
warning if it's called from non-init code.
Link: http://lkml.kernel.org/r/98208db1faf167aa8b08eebfa968d95c70527739.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
elf_kcore_store_hdr() uses __pa() to find the physical address of
KCORE_RAM or KCORE_TEXT entries exported as program headers.
This trips CONFIG_DEBUG_VIRTUAL's checks, as the KCORE_TEXT entries are
not in the linear map.
Handle these two cases separately, using __pa_symbol() for the KCORE_TEXT
entries.
Link: http://lkml.kernel.org/r/20180711131944.15252-1-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use new return type vm_fault_t for fault handler in struct
vm_operations_struct. For now, this is just documenting that the function
returns a VM_FAULT value rather than an errno. Once all instances are
converted, vm_fault_t will become a distinct type.
See 1c8f422059 ("mm: change return type to vm_fault_t") for reference.
Link: http://lkml.kernel.org/r/20180702153325.GA3875@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ganesh Goudar <ganeshgr@chelsio.com>
Cc: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Number of CPUs is never high enough to force 64-bit arithmetic.
Save couple of bytes on x86_64.
Link: http://lkml.kernel.org/r/20180627200710.GC18434@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
->latency_record is defined as
struct latency_record[LT_SAVECOUNT];
so use the same macro whie iterating.
Link: http://lkml.kernel.org/r/20180627200534.GA18434@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Code checks if write is done by current to its own attributes.
For that get/put pair is unnecessary as it can be done under RCU.
Note: rcu_read_unlock() can be done even earlier since pointer to a task
is not dereferenced. It depends if /proc code should look scary or not:
rcu_read_lock();
task = pid_task(...);
rcu_read_unlock();
if (!task)
return -ESRCH;
if (task != current)
return -EACCESS:
P.S.: rename "length" variable. Code like this
length = -EINVAL;
should not exist.
Link: http://lkml.kernel.org/r/20180627200218.GF18113@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Readdir context is thread local, so ->pos is thread local,
move it out of readlock.
Link: http://lkml.kernel.org/r/20180627195339.GD18113@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
get_monotonic_boottime() is deprecated and uses the old timespec type.
Let's convert /proc/uptime to use ktime_get_boottime_ts64().
Link: http://lkml.kernel.org/r/20180620081746.282742-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
24074a35c5 ("proc: Make inline name size calculation automatic")
started to put PDE allocations into kmalloc-256 which is unnecessary as
~40 character names are very rare.
Put allocation back into kmalloc-192 cache for 64-bit non-debug builds.
Put BUILD_BUG_ON to know when PDE size has gotten out of control.
[adobriyan@gmail.com: fix BUILD_BUG_ON breakage on powerpc64]
Link: http://lkml.kernel.org/r/20180703191602.GA25521@avx2
Link: http://lkml.kernel.org/r/20180617215732.GA24688@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, percpu memory only exposes allocation and utilization
information via debugfs. This more or less is only really useful for
understanding the fragmentation and allocation information at a per-chunk
level with a few global counters. This is also gated behind a config.
BPF and cgroup, for example, have seen an increase in use causing
increased use of percpu memory. Let's make it easier for someone to
identify how much memory is being used.
This patch adds the "Percpu" stat to meminfo to more easily look up how
much percpu memory is in use. This number includes the cost for all
allocated backing pages and not just insight at the per a unit, per chunk
level. Metadata is excluded. I think excluding metadata is fair because
the backing memory scales with the numbere of cpus and can quickly
outweigh the metadata. It also makes this calculation light.
Link: http://lkml.kernel.org/r/20180807184723.74919-1-dennisszhou@gmail.com
Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The /proc/pid/smaps_rollup file is currently implemented via the
m_start/m_next/m_stop seq_file iterators shared with the other maps files,
that iterate over vma's. However, the rollup file doesn't print anything
for each vma, only accumulate the stats.
There are some issues with the current code as reported in [1] - the
accumulated stats can get skewed if seq_file start()/stop() op is called
multiple times, if show() is called multiple times, and after seeks to
non-zero position.
Patch [1] fixed those within existing design, but I believe it is
fundamentally wrong to expose the vma iterators to the seq_file mechanism
when smaps_rollup shows logically a single set of values for the whole
address space.
This patch thus refactors the code to provide a single "value" at offset
0, with vma iteration to gather the stats done internally. This fixes the
situations where results are skewed, and simplifies the code, especially
in show_smap(), at the expense of somewhat less code reuse.
[1] https://marc.info/?l=linux-mm&m=151927723128134&w=2
[vbabka@suse.c: use seq_file infrastructure]
Link: http://lkml.kernel.org/r/bf4525b0-fd5b-4c4c-2cb3-adee3dd95a48@suse.cz
Link: http://lkml.kernel.org/r/20180723111933.15443-5-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Daniel Colascione <dancol@google.com>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To prepare for handling /proc/pid/smaps_rollup differently from
/proc/pid/smaps factor out from show_smap() printing the parts of output
that are common for both variants, which is the bulk of the gathered
memory stats.
[vbabka@suse.cz: add const, per Alexey]
Link: http://lkml.kernel.org/r/b45f319f-cd04-337b-37f8-77f99786aa8a@suse.cz
Link: http://lkml.kernel.org/r/20180723111933.15443-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Colascione <dancol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To prepare for handling /proc/pid/smaps_rollup differently from
/proc/pid/smaps factor out vma mem stats gathering from show_smap() - it
will be used by both.
Link: http://lkml.kernel.org/r/20180723111933.15443-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Colascione <dancol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "cleanups and refactor of /proc/pid/smaps*".
The recent regression in /proc/pid/smaps made me look more into the code.
Especially the issues with smaps_rollup reported in [1] as explained in
Patch 4, which fixes them by refactoring the code. Patches 2 and 3 are
preparations for that. Patch 1 is me realizing that there's a lot of
boilerplate left from times where we tried (unsuccessfuly) to mark thread
stacks in the output.
Originally I had also plans to rework the translation from
/proc/pid/*maps* file offsets to the internal structures. Now the offset
means "vma number", which is not really stable (vma's can come and go
between read() calls) and there's an extra caching of last vma's address.
My idea was that offsets would be interpreted directly as addresses, which
would also allow meaningful seeks (see the ugly seek_to_smaps_entry() in
tools/testing/selftests/vm/mlock2.h). However loff_t is (signed) long
long so that might be insufficient somewhere for the unsigned long
addresses.
So the result is fixed issues with skewed /proc/pid/smaps_rollup results,
simpler smaps code, and a lot of unused code removed.
[1] https://marc.info/?l=linux-mm&m=151927723128134&w=2
This patch (of 4):
Commit b76437579d ("procfs: mark thread stack correctly in
proc/<pid>/maps") introduced differences between /proc/PID/maps and
/proc/PID/task/TID/maps to mark thread stacks properly, and this was
also done for smaps and numa_maps. However it didn't work properly and
was ultimately removed by commit b18cb64ead ("fs/proc: Stop trying to
report thread stacks").
Now the is_pid parameter for the related show_*() functions is unused
and we can remove it together with wrapper functions and ops structures
that differ for PID and TID cases only in this parameter.
Link: http://lkml.kernel.org/r/20180723111933.15443-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Colascione <dancol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Without program headers for PTI entry trampoline pages, the trampoline
virtual addresses do not map to anything.
Example before:
sudo gdb --quiet vmlinux /proc/kcore
Reading symbols from vmlinux...done.
[New process 1]
Core was generated by `BOOT_IMAGE=/boot/vmlinuz-4.16.0 root=UUID=a6096b83-b763-4101-807e-f33daff63233'.
#0 0x0000000000000000 in irq_stack_union ()
(gdb) x /21ib 0xfffffe0000006000
0xfffffe0000006000: Cannot access memory at address 0xfffffe0000006000
(gdb) quit
After:
sudo gdb --quiet vmlinux /proc/kcore
[sudo] password for ahunter:
Reading symbols from vmlinux...done.
[New process 1]
Core was generated by `BOOT_IMAGE=/boot/vmlinuz-4.16.0-fix-4-00005-gd6e65a8b4072 root=UUID=a6096b83-b7'.
#0 0x0000000000000000 in irq_stack_union ()
(gdb) x /21ib 0xfffffe0000006000
0xfffffe0000006000: swapgs
0xfffffe0000006003: mov %rsp,-0x3e12(%rip) # 0xfffffe00000021f8
0xfffffe000000600a: xchg %ax,%ax
0xfffffe000000600c: mov %cr3,%rsp
0xfffffe000000600f: bts $0x3f,%rsp
0xfffffe0000006014: and $0xffffffffffffe7ff,%rsp
0xfffffe000000601b: mov %rsp,%cr3
0xfffffe000000601e: mov -0x3019(%rip),%rsp # 0xfffffe000000300c
0xfffffe0000006025: pushq $0x2b
0xfffffe0000006027: pushq -0x3e35(%rip) # 0xfffffe00000021f8
0xfffffe000000602d: push %r11
0xfffffe000000602f: pushq $0x33
0xfffffe0000006031: push %rcx
0xfffffe0000006032: push %rdi
0xfffffe0000006033: mov $0xffffffff91a00010,%rdi
0xfffffe000000603a: callq 0xfffffe0000006046
0xfffffe000000603f: pause
0xfffffe0000006041: lfence
0xfffffe0000006044: jmp 0xfffffe000000603f
0xfffffe0000006046: mov %rdi,(%rsp)
0xfffffe000000604a: retq
(gdb) quit
In addition, entry trampolines all map to the same page. Represent that
by giving the corresponding program headers in kcore the same offset.
This has the benefit that, when perf tools uses /proc/kcore as a source
for kernel object code, samples from different CPU trampolines are
aggregated together. Note, such aggregation is normal for profiling
i.e. people want to profile the object code, not every different virtual
address the object code might be mapped to (across different processes
for example).
Notes by PeterZ:
This also adds the KCORE_REMAP functionality.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/1528289651-4113-4-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Thomas reports:
"While looking around in /proc on my v4.14.52 system I noticed that all
processes got a lot of "Locked" memory in /proc/*/smaps. A lot more
memory than a regular user can usually lock with mlock().
Commit 493b0e9d94 (in v4.14-rc1) seems to have changed the behavior
of "Locked".
Before that commit the code was like this. Notice the VM_LOCKED check.
(vma->vm_flags & VM_LOCKED) ?
(unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
After that commit Locked is now the same as Pss:
(unsigned long)(mss->pss >> (10 + PSS_SHIFT)));
This looks like a mistake."
Indeed, the commit has added mss->pss_locked with the correct value that
depends on VM_LOCKED, but forgot to actually use it. Fix it.
Link: http://lkml.kernel.org/r/ebf6c7fb-fec3-6a26-544f-710ed193c154@suse.cz
Fixes: 493b0e9d94 ("mm: add /proc/pid/smaps_rollup")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs fix from Al Viro:
"Followup to procfs-seq_file series this window"
This fixes a memory leak by making sure that proc seq files release any
private data on close. The 'proc_seq_open' has to be properly paired
with 'proc_seq_release' that releases the extra private data.
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
proc: add proc_seq_release
kmemleak reported some memory leak on reading proc files. After adding
some debug lines, find that proc_seq_fops is using seq_release as
release handler, which won't handle the free of 'private' field of
seq_file, while in fact the open handler proc_seq_open could create
the private data with __seq_open_private when state_size is greater
than zero. So after reading files created with proc_create_seq_private,
such as /proc/timer_list and /proc/vmallocinfo, the private mem of a
seq_file is not freed. Fix it by adding the paired proc_seq_release
as the default release handler of proc_seq_ops instead of seq_release.
Fixes: 44414d82cf ("proc: introduce proc_create_seq_private")
Reviewed-by: Christoph Hellwig <hch@lst.de>
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The rewrite of the cmdline fetching missed the fact that we used to also
return the final terminating NUL character of the last argument. I
hadn't noticed, and none of the tools I tested cared, but something
obviously must care, because Michal Kubecek noticed the change in
behavior.
Tweak the "find the end" logic to actually include the NUL character,
and once past the eend of argv, always start the strnlen() at the
expected (original) argument end.
This whole "allow people to rewrite their arguments in place" is a nasty
hack and requires that odd slop handling at the end of the argv array,
but it's our traditional model, so we continue to support it.
Repored-and-bisected-by: Michal Kubecek <mkubecek@suse.cz>
Reviewed-and-tested-by: Michal Kubecek <mkubecek@suse.cz>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull AFS updates from Al Viro:
"Assorted AFS stuff - ended up in vfs.git since most of that consists
of David's AFS-related followups to Christoph's procfs series"
* 'afs-proc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
afs: Optimise callback breaking by not repeating volume lookup
afs: Display manually added cells in dynamic root mount
afs: Enable IPv6 DNS lookups
afs: Show all of a server's addresses in /proc/fs/afs/servers
afs: Handle CONFIG_PROC_FS=n
proc: Make inline name size calculation automatic
afs: Implement network namespacing
afs: Mark afs_net::ws_cell as __rcu and set using rcu functions
afs: Fix a Sparse warning in xdr_decode_AFSFetchStatus()
proc: Add a way to make network proc files writable
afs: Rearrange fs/afs/proc.c to remove remaining predeclarations.
afs: Rearrange fs/afs/proc.c to move the show routines up
afs: Rearrange fs/afs/proc.c by moving fops and open functions down
afs: Move /proc management functions to the end of the file
Make calculation of the size of the inline name in struct proc_dir_entry
automatic, rather than having to manually encode the numbers and failing to
allow for lockdep.
Require a minimum inline name size of 33+1 to allow for names that look
like two hex numbers with a dash between.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Merge more updates from Andrew Morton:
- MM remainders
- various misc things
- kcov updates
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (27 commits)
lib/test_printf.c: call wait_for_random_bytes() before plain %p tests
hexagon: drop the unused variable zero_page_mask
hexagon: fix printk format warning in setup.c
mm: fix oom_kill event handling
treewide: use PHYS_ADDR_MAX to avoid type casting ULLONG_MAX
mm: use octal not symbolic permissions
ipc: use new return type vm_fault_t
sysvipc/sem: mitigate semnum index against spectre v1
fault-injection: reorder config entries
arm: port KCOV to arm
sched/core / kcov: avoid kcov_area during task switch
kcov: prefault the kcov_area
kcov: ensure irq code sees a valid area
kernel/relay.c: change return type to vm_fault_t
exofs: avoid VLA in structures
coredump: fix spam with zero VMA process
fat: use fat_fs_error() instead of BUG_ON() in __fat_get_block()
proc: skip branch in /proc/*/* lookup
mremap: remove LATENCY_LIMIT from mremap to reduce the number of TLB shootdowns
mm/memblock: add missing include <linux/bootmem.h>
...
Code is structured like this:
for ( ... p < last; p++) {
if (memcmp == 0)
break;
}
if (p >= last)
ERROR
OK
gcc doesn't see that if if lookup succeeds than post loop branch will
never be taken and skip it.
[akpm@linux-foundation.org: proc_pident_instantiate() no longer takes an inode*]
Link: http://lkml.kernel.org/r/20180423213954.GD9043@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a late set of changes from Deepa Dinamani doing an automated
treewide conversion of the inode and iattr structures from 'timespec'
to 'timespec64', to push the conversion from the VFS layer into the
individual file systems.
There were no conflicts between this and the contents of linux-next
until just before the merge window, when we saw multiple problems:
- A minor conflict with my own y2038 fixes, which I could address
by adding another patch on top here.
- One semantic conflict with late changes to the NFS tree. I addressed
this by merging Deepa's original branch on top of the changes that
now got merged into mainline and making sure the merge commit includes
the necessary changes as produced by coccinelle.
- A trivial conflict against the removal of staging/lustre.
- Multiple conflicts against the VFS changes in the overlayfs tree.
These are still part of linux-next, but apparently this is no longer
intended for 4.18 [1], so I am ignoring that part.
As Deepa writes:
The series aims to switch vfs timestamps to use struct timespec64.
Currently vfs uses struct timespec, which is not y2038 safe.
The series involves the following:
1. Add vfs helper functions for supporting struct timepec64 timestamps.
2. Cast prints of vfs timestamps to avoid warnings after the switch.
3. Simplify code using vfs timestamps so that the actual
replacement becomes easy.
4. Convert vfs timestamps to use struct timespec64 using a script.
This is a flag day patch.
Next steps:
1. Convert APIs that can handle timespec64, instead of converting
timestamps at the boundaries.
2. Update internal data structures to avoid timestamp conversions.
Thomas Gleixner adds:
I think there is no point to drag that out for the next merge window.
The whole thing needs to be done in one go for the core changes which
means that you're going to play that catchup game forever. Let's get
over with it towards the end of the merge window.
[1] https://www.spinics.net/lists/linux-fsdevel/msg128294.html
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Merge tag 'vfs-timespec64' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground
Pull inode timestamps conversion to timespec64 from Arnd Bergmann:
"This is a late set of changes from Deepa Dinamani doing an automated
treewide conversion of the inode and iattr structures from 'timespec'
to 'timespec64', to push the conversion from the VFS layer into the
individual file systems.
As Deepa writes:
'The series aims to switch vfs timestamps to use struct timespec64.
Currently vfs uses struct timespec, which is not y2038 safe.
The series involves the following:
1. Add vfs helper functions for supporting struct timepec64
timestamps.
2. Cast prints of vfs timestamps to avoid warnings after the switch.
3. Simplify code using vfs timestamps so that the actual replacement
becomes easy.
4. Convert vfs timestamps to use struct timespec64 using a script.
This is a flag day patch.
Next steps:
1. Convert APIs that can handle timespec64, instead of converting
timestamps at the boundaries.
2. Update internal data structures to avoid timestamp conversions'
Thomas Gleixner adds:
'I think there is no point to drag that out for the next merge
window. The whole thing needs to be done in one go for the core
changes which means that you're going to play that catchup game
forever. Let's get over with it towards the end of the merge window'"
* tag 'vfs-timespec64' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground:
pstore: Remove bogus format string definition
vfs: change inode times to use struct timespec64
pstore: Convert internal records to timespec64
udf: Simplify calls to udf_disk_stamp_to_time
fs: nfs: get rid of memcpys for inode times
ceph: make inode time prints to be long long
lustre: Use long long type to print inode time
fs: add timespec64_truncate()
Pull the timespec64 conversion from Deepa Dinamani:
"The series aims to switch vfs timestamps to use
struct timespec64. Currently vfs uses struct timespec,
which is not y2038 safe.
The flag patch applies cleanly. I've not seen the timestamps
update logic change often. The series applies cleanly on 4.17-rc6
and linux-next tip (top commit: next-20180517).
I'm not sure how to merge this kind of a series with a flag patch.
We are targeting 4.18 for this.
Let me know if you have other suggestions.
The series involves the following:
1. Add vfs helper functions for supporting struct timepec64 timestamps.
2. Cast prints of vfs timestamps to avoid warnings after the switch.
3. Simplify code using vfs timestamps so that the actual
replacement becomes easy.
4. Convert vfs timestamps to use struct timespec64 using a script.
This is a flag day patch.
I've tried to keep the conversions with the script simple, to
aid in the reviews. I've kept all the internal filesystem data
structures and function signatures the same.
Next steps:
1. Convert APIs that can handle timespec64, instead of converting
timestamps at the boundaries.
2. Update internal data structures to avoid timestamp conversions."
I've pulled it into a branch based on top of the NFS changes that
are now in mainline, so I could resolve the non-obvious conflict
between the two while merging.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Merge proc_cmdline simplifications.
This re-writes the get_mm_cmdline() logic to be rather simpler than it
used to be, and makes the semantics for "cmdline goes past the end of
the original area" more natural.
You _can_ use prctl(PR_SET_MM) to just point your command line somewhere
else entirely, but the traditional model is to just edit things in place
and that still needs to continue to work. At least this way the code
makes some sense.
* proc-cmdline:
fs/proc: simplify and clarify get_mm_cmdline() function
fs/proc: re-factor proc_pid_cmdline_read() a bit
Pull proc_fill_cache regression fix from Al Viro:
"Regression fix for proc_fill_cache() braino introduced when switching
instantiate() callback to d_splice_alias()"
* 'work.lookup' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fix proc_fill_cache() in case of d_alloc_parallel() failure
If d_alloc_parallel() returns ERR_PTR(...), we don't want to dput()
that. Small reorganization allows to have all error-in-lookup
cases rejoin the main codepath after dput(child), avoiding the
entire problem.
Spotted-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Fixes: 0168b9e38c "procfs: switch instantiate_t to d_splice_alias()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
