Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 11 Jun 2020 20:30:18 -0700 | Subject | Re: Perf: WARNING: arch/x86/entry/common.c:624 idtentry_exit_cond_rcu+0x92/0xc0 |
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On Thu, Jun 11, 2020 at 4:22 PM Andy Lutomirski <luto@kernel.org> wrote: > > On Thu, Jun 11, 2020 at 12:25 PM Peter Zijlstra <peterz@infradead.org> wrote: > > > > On Thu, Jun 11, 2020 at 12:10:50PM -0700, Andy Lutomirski wrote: > > > On Thu, Jun 11, 2020 at 11:56 AM Naresh Kamboju > > > <naresh.kamboju@linaro.org> wrote: > > > > > > > > While running perf test and selftest x86 single_step_syscall_32 on > > > > i386 kernel linux > > > > next 5.7.0-next-20200610 kernel warning noticed. > > > > > > > > steps to reproduce: > > > > -------------------------- > > > > perf test > > > > and > > > > cd /opt/kselftests/default-in-kernel/x86 > > > > ./single_step_syscall_32 > > > > > > > > perf warning log: > > > > ---------------------- > > > > [ 57.260865] ------------[ cut here ]------------ > > > > [ 57.266576] IRQs not disabled as expected > > > > [ 57.270583] WARNING: CPU: 1 PID: 500 at > > > > /usr/src/kernel/arch/x86/entry/common.c:624 > > > > idtentry_exit_cond_rcu+0x92/0xc0 > > > > [ 57.281092] Modules linked in: x86_pkg_temp_thermal fuse > > > > [ 57.286406] CPU: 1 PID: 500 Comm: perf Not tainted 5.7.0-next-20200610 #1 > > > > [ 57.293190] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS > > > > 2.2 05/23/2018 > > > > [ 57.300577] EIP: idtentry_exit_cond_rcu+0x92/0xc0 > > > > [ 57.305280] Code: 8b 89 d8 05 00 00 85 c9 74 ae 80 3d b1 64 2c d4 > > > > 00 75 a5 68 94 2d fb d3 89 55 f8 89 45 fc c6 05 b1 64 2c d4 01 e8 8e > > > > f5 2b ff <0f> 0b 58 8b 55 f8 8b 45 fc eb 83 8d 76 00 e8 5b fd ff ff c9 > > > > c3 89 > > > > [ 57.324017] EAX: 0000001d EBX: 0d00022a ECX: 00000027 EDX: f5b9e14c > > > > [ 57.330274] ESI: f2a2ffb4 EDI: ffff0ff4 EBP: f2a2ff8c ESP: f2a2ff80 > > > > [ 57.336531] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010096 > > > > [ 57.343345] CR0: 80050033 CR2: 08700a58 CR3: 14ad7000 CR4: 003406d0 > > > > [ 57.349608] DR0: 080dfb80 DR1: 080dfc00 DR2: 08700a58 DR3: 00000000 > > > > [ 57.355866] DR6: fffe0ff0 DR7: 0d00062a > > > > [ 57.359697] Call Trace: > > > > [ 57.362143] exc_debug+0x84/0x1b0 > > > > [ 57.365487] ? exc_int3+0x1d0/0x1d0 > > > > [ 57.368981] handle_exception+0x145/0x145 > > > > [ 57.372991] EIP: 0x80dfbcd > > > > [ 57.375694] Code: Bad RIP value. > > > > [ 57.378918] EAX: 00000000 EBX: 00000005 ECX: 00002400 EDX: 00000000 > > > > [ 57.385175] ESI: 00000003 EDI: 00000004 EBP: bfd59798 ESP: bfd59770 > > > > [ 57.391431] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000246 > > > > [ 57.398215] irq event stamp: 1896 > > > > > > A regrettable property of the current entry code structure is that we > > > lose any real indication of the vector. Presumably this is #DB, hence > > > exc_debug. I don't know what perf has to do with it. > > > > > > I'll bang on this after lunch if no one beats me to it. > > > > Puzzling, CR3 seems to suggest this is !user_mode(), but either way #DB > > has either idtentry_enter_user() or nmi_enter(). > > > > I just got this splat on 32-bit while running my perf abuser here: > > https://git.kernel.org/pub/scm/linux/kernel/git/luto/misc-tests.git/tree/perf_lots_of_nmi.c > > [ 21.874114] traps: PANIC: double fault, error_code: 0x0
Two bugs here.
1. We had an issue with WARN. Patch sent.
2. idtentry.h has, for x86_32:
# define DEFINE_IDTENTRY_IST DEFINE_IDTENTRY
This is nonsense. It's getting late over here and I'd rather focus on the more interesting RCU issue, so that's all from me today.
--Andy
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