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linux-next/kernel
Eiichi Tsukata 46cc0b4442 tracing/snapshot: Resize spare buffer if size changed
Current snapshot implementation swaps two ring_buffers even though their
sizes are different from each other, that can cause an inconsistency
between the contents of buffer_size_kb file and the current buffer size.

For example:

  # cat buffer_size_kb
  7 (expanded: 1408)
  # echo 1 > events/enable
  # grep bytes per_cpu/cpu0/stats
  bytes: 1441020
  # echo 1 > snapshot             // current:1408, spare:1408
  # echo 123 > buffer_size_kb     // current:123,  spare:1408
  # echo 1 > snapshot             // current:1408, spare:123
  # grep bytes per_cpu/cpu0/stats
  bytes: 1443700
  # cat buffer_size_kb
  123                             // != current:1408

And also, a similar per-cpu case hits the following WARNING:

Reproducer:

  # echo 1 > per_cpu/cpu0/snapshot
  # echo 123 > buffer_size_kb
  # echo 1 > per_cpu/cpu0/snapshot

WARNING:

  WARNING: CPU: 0 PID: 1946 at kernel/trace/trace.c:1607 update_max_tr_single.part.0+0x2b8/0x380
  Modules linked in:
  CPU: 0 PID: 1946 Comm: bash Not tainted 5.2.0-rc6 #20
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
  RIP: 0010:update_max_tr_single.part.0+0x2b8/0x380
  Code: ff e8 dc da f9 ff 0f 0b e9 88 fe ff ff e8 d0 da f9 ff 44 89 ee bf f5 ff ff ff e8 33 dc f9 ff 41 83 fd f5 74 96 e8 b8 da f9 ff <0f> 0b eb 8d e8 af da f9 ff 0f 0b e9 bf fd ff ff e8 a3 da f9 ff 48
  RSP: 0018:ffff888063e4fca0 EFLAGS: 00010093
  RAX: ffff888066214380 RBX: ffffffff99850fe0 RCX: ffffffff964298a8
  RDX: 0000000000000000 RSI: 00000000fffffff5 RDI: 0000000000000005
  RBP: 1ffff1100c7c9f96 R08: ffff888066214380 R09: ffffed100c7c9f9b
  R10: ffffed100c7c9f9a R11: 0000000000000003 R12: 0000000000000000
  R13: 00000000ffffffea R14: ffff888066214380 R15: ffffffff99851060
  FS:  00007f9f8173c700(0000) GS:ffff88806d000000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000714dc0 CR3: 0000000066fa6000 CR4: 00000000000006f0
  Call Trace:
   ? trace_array_printk_buf+0x140/0x140
   ? __mutex_lock_slowpath+0x10/0x10
   tracing_snapshot_write+0x4c8/0x7f0
   ? trace_printk_init_buffers+0x60/0x60
   ? selinux_file_permission+0x3b/0x540
   ? tracer_preempt_off+0x38/0x506
   ? trace_printk_init_buffers+0x60/0x60
   __vfs_write+0x81/0x100
   vfs_write+0x1e1/0x560
   ksys_write+0x126/0x250
   ? __ia32_sys_read+0xb0/0xb0
   ? do_syscall_64+0x1f/0x390
   do_syscall_64+0xc1/0x390
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

This patch adds resize_buffer_duplicate_size() to check if there is a
difference between current/spare buffer sizes and resize a spare buffer
if necessary.

Link: http://lkml.kernel.org/r/20190625012910.13109-1-devel@etsukata.com

Cc: stable@vger.kernel.org
Fixes: ad909e21bb ("tracing: Add internal tracing_snapshot() functions")
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-06-28 14:58:52 -04:00
..
bpf bpf: fix undefined behavior in narrow load handling 2019-05-13 02:05:50 +02:00
cgroup kernel/sched/psi.c: expose pressure metrics on root cgroup 2019-05-14 19:52:48 -07:00
configs
debug kdb: Fix bound check compiler warning 2019-05-14 13:44:24 +01:00
dma DMA mapping updates for 5.2 2019-05-09 08:40:55 -07:00
events mm/mmu_notifier: use correct mmu_notifier events for each invalidation 2019-05-14 09:47:49 -07:00
gcov gcov: clang support 2019-05-14 19:52:51 -07:00
irq Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-19 10:58:45 -07:00
livepatch module: Fix livepatch/ftrace module text permissions race 2019-06-14 17:01:50 -04:00
locking locking/rwsem: Prevent decrement of reader count before increment 2019-05-07 08:46:46 +02:00
power Power management updates for 5.2-rc1 2019-05-06 19:40:31 -07:00
printk panic: add an option to replay all the printk message in buffer 2019-05-18 15:52:26 -07:00
rcu The major changes in this tracing update includes: 2019-05-15 16:05:47 -07:00
sched kernel/sched/psi.c: expose pressure metrics on root cgroup 2019-05-14 19:52:48 -07:00
time Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-16 11:00:20 -07:00
trace tracing/snapshot: Resize spare buffer if size changed 2019-06-28 14:58:52 -04:00
.gitignore Provide in-kernel headers to make extending kernel easier 2019-04-29 16:48:03 +02:00
acct.c acct_on(): don't mess with freeze protection 2019-04-04 21:04:13 -04:00
async.c treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively 2019-04-09 14:19:06 +02:00
audit_fsnotify.c audit_compare_dname_path(): switch to const struct qstr * 2019-04-28 20:33:43 -04:00
audit_tree.c fsnotify: switch send_to_group() and ->handle_event to const struct qstr * 2019-04-26 13:51:03 -04:00
audit_watch.c audit_compare_dname_path(): switch to const struct qstr * 2019-04-28 20:33:43 -04:00
audit.c audit: connect LOGIN record to its syscall record 2019-03-20 20:57:48 -04:00
audit.h audit_compare_dname_path(): switch to const struct qstr * 2019-04-28 20:33:43 -04:00
auditfilter.c Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-05-07 20:03:32 -07:00
auditsc.c Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-05-07 20:03:32 -07:00
backtracetest.c backtrace-test: Simplify stack trace handling 2019-04-29 12:37:47 +02:00
bounds.c
capability.c LSM: add SafeSetID module that gates setid calls 2019-01-25 11:22:43 -08:00
compat.c kernel/compat.c: mark expected switch fall-throughs 2019-05-15 08:16:14 -07:00
configs.c kernel/configs: use .incbin directive to embed config_data.gz 2019-03-07 18:32:02 -08:00
context_tracking.c
cpu_pm.c
cpu.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 14:50:46 -07:00
crash_core.c kexec: export PG_offline to VMCOREINFO 2019-03-05 21:07:14 -08:00
crash_dump.c
cred.c SELinux: Remove cred security blob poisoning 2019-01-08 13:18:44 -08:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c mm: change mm_update_next_owner() to update mm->owner with WRITE_ONCE 2019-05-14 19:52:47 -07:00
extable.c
fail_function.c treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively 2019-04-09 14:19:06 +02:00
fork.c kernel/latencytop.c: rename clear_all_latency_tracing to clear_tsk_latency_tracing 2019-05-14 19:52:49 -07:00
freezer.c
futex.c mm/gup: change GUP fast to use flags rather than a write 'bool' 2019-05-14 09:47:46 -07:00
gen_ikh_data.sh Provide in-kernel headers to make extending kernel easier 2019-04-29 16:48:03 +02:00
groups.c
hung_task.c kernel/hung_task.c: Use continuously blocked time when reporting. 2019-03-07 18:31:59 -08:00
iomem.c mm/resource: Use resource_overlaps() to simplify region_intersects() 2019-04-19 12:59:36 +02:00
irq_work.c irq_work: Do not raise an IPI when queueing work on the local CPU 2019-04-18 14:07:52 +02:00
jump_label.c locking/static_key: Don't take sleeping locks in __static_key_slow_dec_deferred() 2019-04-29 08:29:21 +02:00
kallsyms.c bpf: Add module name [bpf] to ksymbols for bpf programs 2019-01-21 17:38:56 -03:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks Remove Mysterious Macro Intended to Obscure Weird Behaviours (mmiowb()) 2019-05-06 16:57:52 -07:00
Kconfig.preempt kconfig: warn no new line at end of file 2018-12-15 17:44:35 +09:00
kcov.c kcov: convert kcov.refcount to refcount_t 2019-03-07 18:32:02 -08:00
kexec_core.c power/suspend: Add function to disable secondaries for suspend 2019-05-03 19:42:41 +02:00
kexec_file.c mm: memblock: make keeping memblock memory opt-in rather than opt-out 2019-05-14 09:47:50 -07:00
kexec_internal.h
kexec.c
kheaders.c Provide in-kernel headers to make extending kernel easier 2019-04-29 16:48:03 +02:00
kmod.c
kprobes.c kprobes: Fix error check when reusing optimized probes 2019-04-16 09:38:16 +02:00
ksysfs.c
kthread.c include/: refactor headers to allow kthread.h inclusion in psi_types.h 2019-05-14 19:52:48 -07:00
latencytop.c kernel/latencytop.c: rename clear_all_latency_tracing to clear_tsk_latency_tracing 2019-05-14 19:52:49 -07:00
Makefile kernel/Makefile: don't assume that kernel/gen_ikh_data.sh is executable 2019-05-14 19:52:47 -07:00
memremap.c kernel/memremap.c: remove the unused device_private_entry_fault() export 2019-05-14 09:47:51 -07:00
module_signing.c modsign: use all trusted keys to verify module signature 2018-11-07 14:41:41 +01:00
module-internal.h kallsyms: store type information in its own array 2019-03-28 15:00:37 +01:00
module.c Modules updates for v5.2 2019-05-14 10:55:54 -07:00
notifier.c kernel/notifier.c: double register detection 2019-05-14 19:52:49 -07:00
nsproxy.c
padata.c padata: Replace padata_attr_type default_attrs field with groups 2019-04-25 22:06:11 +02:00
panic.c panic: add an option to replay all the printk message in buffer 2019-05-18 15:52:26 -07:00
params.c
pid_namespace.c
pid.c kernel/pid.c: remove unneeded hash header file 2019-05-14 19:52:51 -07:00
profile.c
ptrace.c ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK 2019-03-29 10:01:37 -07:00
range.c
reboot.c panic/reboot: allow specifying reboot_mode for panic only 2019-05-14 19:52:51 -07:00
relay.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-03-12 13:27:20 -07:00
resource.c mm/resource: Use resource_overlaps() to simplify region_intersects() 2019-04-19 12:59:36 +02:00
rseq.c rseq: Remove superfluous rseq_len from task_struct 2019-04-19 12:39:32 +02:00
seccomp.c audit/stable-5.2 PR 20190507 2019-05-07 19:06:04 -07:00
signal.c signal: unconditionally leave the frozen state in ptrace_stop() 2019-05-16 10:43:58 -07:00
smp.c cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM 2019-01-30 19:27:00 +01:00
smpboot.c
smpboot.h
softirq.c softirq: Remove tasklet_hrtimer 2019-03-22 14:36:02 +01:00
stackleak.c stackleak: Mark stackleak_track_stack() as notrace 2018-12-05 19:31:44 -08:00
stacktrace.c stacktrace: Provide common infrastructure 2019-04-29 12:37:57 +02:00
stop_machine.c treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively 2019-04-09 14:19:06 +02:00
sys_ni.c signal: support CLONE_PIDFD with pidfd_send_signal 2019-05-07 14:31:03 +02:00
sys.c kernel/sys.c: prctl: fix false positive in validate_prctl_map() 2019-05-14 09:47:44 -07:00
sysctl_binary.c kernel/sysctl: add panic_print into sysctl 2019-01-04 13:13:47 -08:00
sysctl.c kernel/sysctl.c: fix proc_do_large_bitmap for large input buffers 2019-05-14 19:52:51 -07:00
task_work.c
taskstats.c genetlink: optionally validate strictly/dumps 2019-04-27 17:07:22 -04:00
test_kprobes.c
torture.c torture: Don't try to offline the last CPU 2019-03-26 14:42:53 -07:00
tracepoint.c tracing: Replace synchronize_sched() and call_rcu_sched() 2018-11-27 09:21:41 -08:00
tsacct.c
ucount.c
uid16.c
uid16.h
umh.c umh: add exit routine for UMH process 2019-01-11 18:05:40 -08:00
up.c
user_namespace.c userns: also map extents in the reverse map to kernel IDs 2018-11-07 23:51:16 -06:00
user-return-notifier.c
user.c kernel/user.c: clean up some leftover code 2019-05-14 19:52:49 -07:00
utsname_sysctl.c
utsname.c
watchdog_hld.c kernel/watchdog_hld.c: hard lockup message should end with a newline 2019-04-19 09:46:05 -07:00
watchdog.c watchdog: Fix typo in comment 2019-04-18 14:05:51 +02:00
workqueue_internal.h sched/core, workqueues: Distangle worker accounting from rq lock 2019-04-16 16:55:15 +02:00
workqueue.c Merge branch 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2019-05-09 13:48:52 -07:00