* WARNING: suspicious RCU usage in count @ 2020-12-16 19:34 syzbot 2020-12-16 20:55 ` Matthew Wilcox 0 siblings, 1 reply; 4+ messages in thread From: syzbot @ 2020-12-16 19:34 UTC (permalink / raw) To: linux-fsdevel, linux-kernel, syzkaller-bugs, viro Hello, syzbot found the following issue on: HEAD commit: 7f376f19 Merge tag 'mtd/fixes-for-5.10-rc8' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1217bb7f500000 kernel config: https://syzkaller.appspot.com/x/.config?x=ee8a1012a5314210 dashboard link: https://syzkaller.appspot.com/bug?extid=51ce7a5794c3b12a70d1 compiler: gcc (GCC) 10.1.0-syz 20200507 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+51ce7a5794c3b12a70d1@syzkaller.appspotmail.com ============================= WARNING: suspicious RCU usage 5.10.0-rc7-syzkaller #0 Not tainted ----------------------------- kernel/sched/core.c:7270 Illegal context switch in RCU-bh read-side critical section! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 0 no locks held by udevd/9038. stack backtrace: CPU: 3 PID: 9038 Comm: udevd Not tainted 5.10.0-rc7-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:118 ___might_sleep+0x220/0x2b0 kernel/sched/core.c:7270 count.constprop.0+0x164/0x270 fs/exec.c:449 do_execveat_common+0x2fd/0x7c0 fs/exec.c:1893 do_execve fs/exec.c:1983 [inline] __do_sys_execve fs/exec.c:2059 [inline] __se_sys_execve fs/exec.c:2054 [inline] __x64_sys_execve+0x8f/0xc0 fs/exec.c:2054 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7fbc6f64c207 Code: 77 19 f4 48 89 d7 44 89 c0 0f 05 48 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 f7 d8 64 41 89 01 eb df b8 3b 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 02 f3 c3 48 8b 15 00 8c 2d 00 f7 d8 64 89 02 RSP: 002b:00007ffcfe4966d8 EFLAGS: 00000206 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fbc6f64c207 RDX: 0000000000f1dfd0 RSI: 00007ffcfe4967d0 RDI: 00007ffcfe4977e0 RBP: 0000000000625500 R08: 00000000000022fb R09: 00000000000022fb R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000f1dfd0 R13: 0000000000000007 R14: 0000000000f0e250 R15: 0000000000000005 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: WARNING: suspicious RCU usage in count 2020-12-16 19:34 WARNING: suspicious RCU usage in count syzbot @ 2020-12-16 20:55 ` Matthew Wilcox 2020-12-17 8:26 ` Dmitry Vyukov 0 siblings, 1 reply; 4+ messages in thread From: Matthew Wilcox @ 2020-12-16 20:55 UTC (permalink / raw) To: syzbot; +Cc: linux-fsdevel, linux-kernel, syzkaller-bugs, viro On Wed, Dec 16, 2020 at 11:34:10AM -0800, syzbot wrote: > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+51ce7a5794c3b12a70d1@syzkaller.appspotmail.com > > ============================= > WARNING: suspicious RCU usage > 5.10.0-rc7-syzkaller #0 Not tainted > ----------------------------- > kernel/sched/core.c:7270 Illegal context switch in RCU-bh read-side critical section! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 0 > no locks held by udevd/9038. > > stack backtrace: > CPU: 3 PID: 9038 Comm: udevd Not tainted 5.10.0-rc7-syzkaller #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:118 > ___might_sleep+0x220/0x2b0 kernel/sched/core.c:7270 > count.constprop.0+0x164/0x270 fs/exec.c:449 > do_execveat_common+0x2fd/0x7c0 fs/exec.c:1893 > do_execve fs/exec.c:1983 [inline] > __do_sys_execve fs/exec.c:2059 [inline] > __se_sys_execve fs/exec.c:2054 [inline] > __x64_sys_execve+0x8f/0xc0 fs/exec.c:2054 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 This must be the victim of something else. There's no way this call trace took the RCU read lock. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: WARNING: suspicious RCU usage in count 2020-12-16 20:55 ` Matthew Wilcox @ 2020-12-17 8:26 ` Dmitry Vyukov 2020-12-17 15:19 ` Paul E. McKenney 0 siblings, 1 reply; 4+ messages in thread From: Dmitry Vyukov @ 2020-12-17 8:26 UTC (permalink / raw) To: Matthew Wilcox, Peter Zijlstra, Ingo Molnar, Will Deacon, Paul E. McKenney Cc: syzbot, linux-fsdevel, LKML, syzkaller-bugs, Al Viro On Wed, Dec 16, 2020 at 9:55 PM Matthew Wilcox <willy@infradead.org> wrote: > > On Wed, Dec 16, 2020 at 11:34:10AM -0800, syzbot wrote: > > Unfortunately, I don't have any reproducer for this issue yet. > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+51ce7a5794c3b12a70d1@syzkaller.appspotmail.com > > > > ============================= > > WARNING: suspicious RCU usage > > 5.10.0-rc7-syzkaller #0 Not tainted > > ----------------------------- > > kernel/sched/core.c:7270 Illegal context switch in RCU-bh read-side critical section! > > > > other info that might help us debug this: > > > > > > rcu_scheduler_active = 2, debug_locks = 0 > > no locks held by udevd/9038. > > > > stack backtrace: > > CPU: 3 PID: 9038 Comm: udevd Not tainted 5.10.0-rc7-syzkaller #0 > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0x107/0x163 lib/dump_stack.c:118 > > ___might_sleep+0x220/0x2b0 kernel/sched/core.c:7270 > > count.constprop.0+0x164/0x270 fs/exec.c:449 > > do_execveat_common+0x2fd/0x7c0 fs/exec.c:1893 > > do_execve fs/exec.c:1983 [inline] > > __do_sys_execve fs/exec.c:2059 [inline] > > __se_sys_execve fs/exec.c:2054 [inline] > > __x64_sys_execve+0x8f/0xc0 fs/exec.c:2054 > > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > > This must be the victim of something else. There's no way this call > trace took the RCU read lock. +lockdep maintainers for lockdep false positive then and +Paul for rcu There is another recent claim of a false "suspicious RCU usage": https://lore.kernel.org/lkml/CAKMK7uEiS5SrBYv-2w2wWL=9G4ByoHvtiWVsPqekswZzOGmzjg@mail.gmail.com/ ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: WARNING: suspicious RCU usage in count 2020-12-17 8:26 ` Dmitry Vyukov @ 2020-12-17 15:19 ` Paul E. McKenney 0 siblings, 0 replies; 4+ messages in thread From: Paul E. McKenney @ 2020-12-17 15:19 UTC (permalink / raw) To: Dmitry Vyukov Cc: Matthew Wilcox, Peter Zijlstra, Ingo Molnar, Will Deacon, syzbot, linux-fsdevel, LKML, syzkaller-bugs, Al Viro On Thu, Dec 17, 2020 at 09:26:44AM +0100, Dmitry Vyukov wrote: > On Wed, Dec 16, 2020 at 9:55 PM Matthew Wilcox <willy@infradead.org> wrote: > > > > On Wed, Dec 16, 2020 at 11:34:10AM -0800, syzbot wrote: > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+51ce7a5794c3b12a70d1@syzkaller.appspotmail.com > > > > > > ============================= > > > WARNING: suspicious RCU usage > > > 5.10.0-rc7-syzkaller #0 Not tainted > > > ----------------------------- > > > kernel/sched/core.c:7270 Illegal context switch in RCU-bh read-side critical section! > > > > > > other info that might help us debug this: > > > > > > > > > rcu_scheduler_active = 2, debug_locks = 0 > > > no locks held by udevd/9038. > > > > > > stack backtrace: > > > CPU: 3 PID: 9038 Comm: udevd Not tainted 5.10.0-rc7-syzkaller #0 > > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 > > > Call Trace: > > > __dump_stack lib/dump_stack.c:77 [inline] > > > dump_stack+0x107/0x163 lib/dump_stack.c:118 > > > ___might_sleep+0x220/0x2b0 kernel/sched/core.c:7270 > > > count.constprop.0+0x164/0x270 fs/exec.c:449 > > > do_execveat_common+0x2fd/0x7c0 fs/exec.c:1893 > > > do_execve fs/exec.c:1983 [inline] > > > __do_sys_execve fs/exec.c:2059 [inline] > > > __se_sys_execve fs/exec.c:2054 [inline] > > > __x64_sys_execve+0x8f/0xc0 fs/exec.c:2054 > > > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 > > > > This must be the victim of something else. There's no way this call > > trace took the RCU read lock. > > +lockdep maintainers for lockdep false positive then and +Paul for rcu Note that this was "RCU-bh" rather than "RCU", so it might be something like local_bh_disable() rather than rcu_read_lock() that might_sleep() is complaining about. > There is another recent claim of a false "suspicious RCU usage": > https://lore.kernel.org/lkml/CAKMK7uEiS5SrBYv-2w2wWL=9G4ByoHvtiWVsPqekswZzOGmzjg@mail.gmail.com/ That one does look familiar. ;-) Thanx, Paul ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-12-17 15:20 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2020-12-16 19:34 WARNING: suspicious RCU usage in count syzbot 2020-12-16 20:55 ` Matthew Wilcox 2020-12-17 8:26 ` Dmitry Vyukov 2020-12-17 15:19 ` Paul E. McKenney
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