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46cc0b4442
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:
|
||
|---|---|---|
| .. | ||
| bpf | ||
| cgroup | ||
| configs | ||
| debug | ||
| dma | ||
| events | ||
| gcov | ||
| irq | ||
| livepatch | ||
| locking | ||
| power | ||
| printk | ||
| rcu | ||
| sched | ||
| time | ||
| trace | ||
| .gitignore | ||
| acct.c | ||
| async.c | ||
| audit.c | ||
| audit.h | ||
| audit_fsnotify.c | ||
| audit_tree.c | ||
| audit_watch.c | ||
| auditfilter.c | ||
| auditsc.c | ||
| backtracetest.c | ||
| bounds.c | ||
| capability.c | ||
| compat.c | ||
| configs.c | ||
| context_tracking.c | ||
| cpu.c | ||
| cpu_pm.c | ||
| crash_core.c | ||
| crash_dump.c | ||
| cred.c | ||
| delayacct.c | ||
| dma.c | ||
| elfcore.c | ||
| exec_domain.c | ||
| exit.c | ||
| extable.c | ||
| fail_function.c | ||
| fork.c | ||
| freezer.c | ||
| futex.c | ||
| gen_ikh_data.sh | ||
| groups.c | ||
| hung_task.c | ||
| iomem.c | ||
| irq_work.c | ||
| jump_label.c | ||
| kallsyms.c | ||
| kcmp.c | ||
| Kconfig.freezer | ||
| Kconfig.hz | ||
| Kconfig.locks | ||
| Kconfig.preempt | ||
| kcov.c | ||
| kexec.c | ||
| kexec_core.c | ||
| kexec_file.c | ||
| kexec_internal.h | ||
| kheaders.c | ||
| kmod.c | ||
| kprobes.c | ||
| ksysfs.c | ||
| kthread.c | ||
| latencytop.c | ||
| Makefile | ||
| memremap.c | ||
| module-internal.h | ||
| module.c | ||
| module_signing.c | ||
| notifier.c | ||
| nsproxy.c | ||
| padata.c | ||
| panic.c | ||
| params.c | ||
| pid.c | ||
| pid_namespace.c | ||
| profile.c | ||
| ptrace.c | ||
| range.c | ||
| reboot.c | ||
| relay.c | ||
| resource.c | ||
| rseq.c | ||
| seccomp.c | ||
| signal.c | ||
| smp.c | ||
| smpboot.c | ||
| smpboot.h | ||
| softirq.c | ||
| stackleak.c | ||
| stacktrace.c | ||
| stop_machine.c | ||
| sys.c | ||
| sys_ni.c | ||
| sysctl.c | ||
| sysctl_binary.c | ||
| task_work.c | ||
| taskstats.c | ||
| test_kprobes.c | ||
| torture.c | ||
| tracepoint.c | ||
| tsacct.c | ||
| ucount.c | ||
| uid16.c | ||
| uid16.h | ||
| umh.c | ||
| up.c | ||
| user-return-notifier.c | ||
| user.c | ||
| user_namespace.c | ||
| utsname.c | ||
| utsname_sysctl.c | ||
| watchdog.c | ||
| watchdog_hld.c | ||
| workqueue.c | ||
| workqueue_internal.h | ||