* [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit
@ 2021-09-21 6:40 Dave Chinner
2021-09-21 13:25 ` Jens Axboe
0 siblings, 1 reply; 6+ messages in thread
From: Dave Chinner @ 2021-09-21 6:40 UTC (permalink / raw)
To: Jens Axboe; +Cc: io-uring, linux-fsdevel
Hi Jens,
I updated all my trees from 5.14 to 5.15-rc2 this morning and
immediately had problems running the recoveryloop fstest group on
them. These tests have a typical pattern of "run load in the
background, shutdown the filesystem, kill load, unmount and test
recovery".
Whent eh load includes fsstress, and it gets killed after shutdown,
it hangs on exit like so:
# echo w > /proc/sysrq-trigger
[ 370.669482] sysrq: Show Blocked State
[ 370.671732] task:fsstress state:D stack:11088 pid: 9619 ppid: 9615 flags:0x00000000
[ 370.675870] Call Trace:
[ 370.677067] __schedule+0x310/0x9f0
[ 370.678564] schedule+0x67/0xe0
[ 370.679545] schedule_timeout+0x114/0x160
[ 370.682002] __wait_for_common+0xc0/0x160
[ 370.684274] wait_for_completion+0x24/0x30
[ 370.685471] do_coredump+0x202/0x1150
[ 370.690270] get_signal+0x4c2/0x900
[ 370.691305] arch_do_signal_or_restart+0x106/0x7a0
[ 370.693888] exit_to_user_mode_prepare+0xfb/0x1d0
[ 370.695241] syscall_exit_to_user_mode+0x17/0x40
[ 370.696572] do_syscall_64+0x42/0x80
[ 370.697620] entry_SYSCALL_64_after_hwframe+0x44/0xae
It's 100% reproducable on one of my test machines, but only one of
them. That one machine is running fstests on pmem, so it has
synchronous storage. Every other test machine using normal async
storage (nvme, iscsi, etc) and none of them are hanging.
A quick troll of the commit history between 5.14 and 5.15-rc2
indicates a couple of potential candidates. The 5th kernel build
(instead of ~16 for a bisect) told me that commit 15e20db2e0ce
("io-wq: only exit on fatal signals") is the cause of the
regression. I've confirmed that this is the first commit where the
problem shows up.
Cheers,
Dave.
--
Dave Chinner
[email protected]
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit 2021-09-21 6:40 [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit Dave Chinner @ 2021-09-21 13:25 ` Jens Axboe 2021-09-21 14:19 ` Jens Axboe 0 siblings, 1 reply; 6+ messages in thread From: Jens Axboe @ 2021-09-21 13:25 UTC (permalink / raw) To: Dave Chinner; +Cc: io-uring, linux-fsdevel On 9/21/21 12:40 AM, Dave Chinner wrote: > Hi Jens, > > I updated all my trees from 5.14 to 5.15-rc2 this morning and > immediately had problems running the recoveryloop fstest group on > them. These tests have a typical pattern of "run load in the > background, shutdown the filesystem, kill load, unmount and test > recovery". > > Whent eh load includes fsstress, and it gets killed after shutdown, > it hangs on exit like so: > > # echo w > /proc/sysrq-trigger > [ 370.669482] sysrq: Show Blocked State > [ 370.671732] task:fsstress state:D stack:11088 pid: 9619 ppid: 9615 flags:0x00000000 > [ 370.675870] Call Trace: > [ 370.677067] __schedule+0x310/0x9f0 > [ 370.678564] schedule+0x67/0xe0 > [ 370.679545] schedule_timeout+0x114/0x160 > [ 370.682002] __wait_for_common+0xc0/0x160 > [ 370.684274] wait_for_completion+0x24/0x30 > [ 370.685471] do_coredump+0x202/0x1150 > [ 370.690270] get_signal+0x4c2/0x900 > [ 370.691305] arch_do_signal_or_restart+0x106/0x7a0 > [ 370.693888] exit_to_user_mode_prepare+0xfb/0x1d0 > [ 370.695241] syscall_exit_to_user_mode+0x17/0x40 > [ 370.696572] do_syscall_64+0x42/0x80 > [ 370.697620] entry_SYSCALL_64_after_hwframe+0x44/0xae > > It's 100% reproducable on one of my test machines, but only one of > them. That one machine is running fstests on pmem, so it has > synchronous storage. Every other test machine using normal async > storage (nvme, iscsi, etc) and none of them are hanging. > > A quick troll of the commit history between 5.14 and 5.15-rc2 > indicates a couple of potential candidates. The 5th kernel build > (instead of ~16 for a bisect) told me that commit 15e20db2e0ce > ("io-wq: only exit on fatal signals") is the cause of the > regression. I've confirmed that this is the first commit where the > problem shows up. Thanks for the report Dave, I'll take a look. Can you elaborate on exactly what is being run? And when killed, it's a non-fatal signal? -- Jens Axboe ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit 2021-09-21 13:25 ` Jens Axboe @ 2021-09-21 14:19 ` Jens Axboe 2021-09-21 21:35 ` Dave Chinner 0 siblings, 1 reply; 6+ messages in thread From: Jens Axboe @ 2021-09-21 14:19 UTC (permalink / raw) To: Dave Chinner; +Cc: io-uring, linux-fsdevel On 9/21/21 7:25 AM, Jens Axboe wrote: > On 9/21/21 12:40 AM, Dave Chinner wrote: >> Hi Jens, >> >> I updated all my trees from 5.14 to 5.15-rc2 this morning and >> immediately had problems running the recoveryloop fstest group on >> them. These tests have a typical pattern of "run load in the >> background, shutdown the filesystem, kill load, unmount and test >> recovery". >> >> Whent eh load includes fsstress, and it gets killed after shutdown, >> it hangs on exit like so: >> >> # echo w > /proc/sysrq-trigger >> [ 370.669482] sysrq: Show Blocked State >> [ 370.671732] task:fsstress state:D stack:11088 pid: 9619 ppid: 9615 flags:0x00000000 >> [ 370.675870] Call Trace: >> [ 370.677067] __schedule+0x310/0x9f0 >> [ 370.678564] schedule+0x67/0xe0 >> [ 370.679545] schedule_timeout+0x114/0x160 >> [ 370.682002] __wait_for_common+0xc0/0x160 >> [ 370.684274] wait_for_completion+0x24/0x30 >> [ 370.685471] do_coredump+0x202/0x1150 >> [ 370.690270] get_signal+0x4c2/0x900 >> [ 370.691305] arch_do_signal_or_restart+0x106/0x7a0 >> [ 370.693888] exit_to_user_mode_prepare+0xfb/0x1d0 >> [ 370.695241] syscall_exit_to_user_mode+0x17/0x40 >> [ 370.696572] do_syscall_64+0x42/0x80 >> [ 370.697620] entry_SYSCALL_64_after_hwframe+0x44/0xae >> >> It's 100% reproducable on one of my test machines, but only one of >> them. That one machine is running fstests on pmem, so it has >> synchronous storage. Every other test machine using normal async >> storage (nvme, iscsi, etc) and none of them are hanging. >> >> A quick troll of the commit history between 5.14 and 5.15-rc2 >> indicates a couple of potential candidates. The 5th kernel build >> (instead of ~16 for a bisect) told me that commit 15e20db2e0ce >> ("io-wq: only exit on fatal signals") is the cause of the >> regression. I've confirmed that this is the first commit where the >> problem shows up. > > Thanks for the report Dave, I'll take a look. Can you elaborate on > exactly what is being run? And when killed, it's a non-fatal signal? Can you try with this patch? diff --git a/fs/io-wq.c b/fs/io-wq.c index b5fd015268d7..1e55a0a2a217 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -586,7 +586,8 @@ static int io_wqe_worker(void *data) if (!get_signal(&ksig)) continue; - if (fatal_signal_pending(current)) + if (fatal_signal_pending(current) || + signal_group_exit(current->signal)) { break; continue; } -- Jens Axboe ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit 2021-09-21 14:19 ` Jens Axboe @ 2021-09-21 21:35 ` Dave Chinner 2021-09-21 21:41 ` Jens Axboe 0 siblings, 1 reply; 6+ messages in thread From: Dave Chinner @ 2021-09-21 21:35 UTC (permalink / raw) To: Jens Axboe; +Cc: io-uring, linux-fsdevel On Tue, Sep 21, 2021 at 08:19:53AM -0600, Jens Axboe wrote: > On 9/21/21 7:25 AM, Jens Axboe wrote: > > On 9/21/21 12:40 AM, Dave Chinner wrote: > >> Hi Jens, > >> > >> I updated all my trees from 5.14 to 5.15-rc2 this morning and > >> immediately had problems running the recoveryloop fstest group on > >> them. These tests have a typical pattern of "run load in the > >> background, shutdown the filesystem, kill load, unmount and test > >> recovery". > >> > >> Whent eh load includes fsstress, and it gets killed after shutdown, > >> it hangs on exit like so: > >> > >> # echo w > /proc/sysrq-trigger > >> [ 370.669482] sysrq: Show Blocked State > >> [ 370.671732] task:fsstress state:D stack:11088 pid: 9619 ppid: 9615 flags:0x00000000 > >> [ 370.675870] Call Trace: > >> [ 370.677067] __schedule+0x310/0x9f0 > >> [ 370.678564] schedule+0x67/0xe0 > >> [ 370.679545] schedule_timeout+0x114/0x160 > >> [ 370.682002] __wait_for_common+0xc0/0x160 > >> [ 370.684274] wait_for_completion+0x24/0x30 > >> [ 370.685471] do_coredump+0x202/0x1150 > >> [ 370.690270] get_signal+0x4c2/0x900 > >> [ 370.691305] arch_do_signal_or_restart+0x106/0x7a0 > >> [ 370.693888] exit_to_user_mode_prepare+0xfb/0x1d0 > >> [ 370.695241] syscall_exit_to_user_mode+0x17/0x40 > >> [ 370.696572] do_syscall_64+0x42/0x80 > >> [ 370.697620] entry_SYSCALL_64_after_hwframe+0x44/0xae > >> > >> It's 100% reproducable on one of my test machines, but only one of > >> them. That one machine is running fstests on pmem, so it has > >> synchronous storage. Every other test machine using normal async > >> storage (nvme, iscsi, etc) and none of them are hanging. > >> > >> A quick troll of the commit history between 5.14 and 5.15-rc2 > >> indicates a couple of potential candidates. The 5th kernel build > >> (instead of ~16 for a bisect) told me that commit 15e20db2e0ce > >> ("io-wq: only exit on fatal signals") is the cause of the > >> regression. I've confirmed that this is the first commit where the > >> problem shows up. > > > > Thanks for the report Dave, I'll take a look. Can you elaborate on > > exactly what is being run? And when killed, it's a non-fatal signal? It's whatever kill/killall sends by default. Typical behaviour that causes a hang is something like: $FSSTRESS_PROG -n10000000 -p $PROCS -d $load_dir >> $seqres.full 2>&1 & .... sleep 5 _scratch_shutdown $KILLALL_PROG -q $FSSTRESS_PROG wait _shutdown_scratch is typically just an 'xfs_io -rx -c "shutdown" /mnt/scratch' command that shuts down the filesystem. Other tests in the recoveryloop group use DM targets to fail IO that trigger a shutdown, others inject errors that trigger shutdowns, etc. But the result is that all hang waiting for fsstress processes that have been using io_uring to exit. Just run fstests with "./check -g recoveryloop" - there's only a handful of tests and it only takes about 5 minutes to run them all on a fake DRAM based pmem device.. > Can you try with this patch? > > diff --git a/fs/io-wq.c b/fs/io-wq.c > index b5fd015268d7..1e55a0a2a217 100644 > --- a/fs/io-wq.c > +++ b/fs/io-wq.c > @@ -586,7 +586,8 @@ static int io_wqe_worker(void *data) > > if (!get_signal(&ksig)) > continue; > - if (fatal_signal_pending(current)) > + if (fatal_signal_pending(current) || > + signal_group_exit(current->signal)) { > break; > continue; > } Cleaned up so it compiles and the tests run properly again. But playing whack-a-mole with signals seems kinda fragile. I was pointed to this patchset by another dev on #xfs overnight who saw the same hangs that also fixed the hang: https://lore.kernel.org/lkml/[email protected]/ It was posted about a month ago and I don't see any response to it on the lists... Cheers, Dave, -- Dave Chinner [email protected] ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit 2021-09-21 21:35 ` Dave Chinner @ 2021-09-21 21:41 ` Jens Axboe 2021-09-23 14:05 ` Olivier Langlois 0 siblings, 1 reply; 6+ messages in thread From: Jens Axboe @ 2021-09-21 21:41 UTC (permalink / raw) To: Dave Chinner; +Cc: io-uring, linux-fsdevel On 9/21/21 3:35 PM, Dave Chinner wrote: > On Tue, Sep 21, 2021 at 08:19:53AM -0600, Jens Axboe wrote: >> On 9/21/21 7:25 AM, Jens Axboe wrote: >>> On 9/21/21 12:40 AM, Dave Chinner wrote: >>>> Hi Jens, >>>> >>>> I updated all my trees from 5.14 to 5.15-rc2 this morning and >>>> immediately had problems running the recoveryloop fstest group on >>>> them. These tests have a typical pattern of "run load in the >>>> background, shutdown the filesystem, kill load, unmount and test >>>> recovery". >>>> >>>> Whent eh load includes fsstress, and it gets killed after shutdown, >>>> it hangs on exit like so: >>>> >>>> # echo w > /proc/sysrq-trigger >>>> [ 370.669482] sysrq: Show Blocked State >>>> [ 370.671732] task:fsstress state:D stack:11088 pid: 9619 ppid: 9615 flags:0x00000000 >>>> [ 370.675870] Call Trace: >>>> [ 370.677067] __schedule+0x310/0x9f0 >>>> [ 370.678564] schedule+0x67/0xe0 >>>> [ 370.679545] schedule_timeout+0x114/0x160 >>>> [ 370.682002] __wait_for_common+0xc0/0x160 >>>> [ 370.684274] wait_for_completion+0x24/0x30 >>>> [ 370.685471] do_coredump+0x202/0x1150 >>>> [ 370.690270] get_signal+0x4c2/0x900 >>>> [ 370.691305] arch_do_signal_or_restart+0x106/0x7a0 >>>> [ 370.693888] exit_to_user_mode_prepare+0xfb/0x1d0 >>>> [ 370.695241] syscall_exit_to_user_mode+0x17/0x40 >>>> [ 370.696572] do_syscall_64+0x42/0x80 >>>> [ 370.697620] entry_SYSCALL_64_after_hwframe+0x44/0xae >>>> >>>> It's 100% reproducable on one of my test machines, but only one of >>>> them. That one machine is running fstests on pmem, so it has >>>> synchronous storage. Every other test machine using normal async >>>> storage (nvme, iscsi, etc) and none of them are hanging. >>>> >>>> A quick troll of the commit history between 5.14 and 5.15-rc2 >>>> indicates a couple of potential candidates. The 5th kernel build >>>> (instead of ~16 for a bisect) told me that commit 15e20db2e0ce >>>> ("io-wq: only exit on fatal signals") is the cause of the >>>> regression. I've confirmed that this is the first commit where the >>>> problem shows up. >>> >>> Thanks for the report Dave, I'll take a look. Can you elaborate on >>> exactly what is being run? And when killed, it's a non-fatal signal? > > It's whatever kill/killall sends by default. Typical behaviour that > causes a hang is something like: > > $FSSTRESS_PROG -n10000000 -p $PROCS -d $load_dir >> $seqres.full 2>&1 & > .... > sleep 5 > _scratch_shutdown > $KILLALL_PROG -q $FSSTRESS_PROG > wait > > _shutdown_scratch is typically just an 'xfs_io -rx -c "shutdown" > /mnt/scratch' command that shuts down the filesystem. Other tests in > the recoveryloop group use DM targets to fail IO that trigger a > shutdown, others inject errors that trigger shutdowns, etc. But the > result is that all hang waiting for fsstress processes that have > been using io_uring to exit. > > Just run fstests with "./check -g recoveryloop" - there's only a > handful of tests and it only takes about 5 minutes to run them all > on a fake DRAM based pmem device.. I made a trivial reproducer just to verify. >> Can you try with this patch? >> >> diff --git a/fs/io-wq.c b/fs/io-wq.c >> index b5fd015268d7..1e55a0a2a217 100644 >> --- a/fs/io-wq.c >> +++ b/fs/io-wq.c >> @@ -586,7 +586,8 @@ static int io_wqe_worker(void *data) >> >> if (!get_signal(&ksig)) >> continue; >> - if (fatal_signal_pending(current)) >> + if (fatal_signal_pending(current) || >> + signal_group_exit(current->signal)) { >> break; >> continue; >> } > > Cleaned up so it compiles and the tests run properly again. But > playing whack-a-mole with signals seems kinda fragile. I was pointed > to this patchset by another dev on #xfs overnight who saw the same > hangs that also fixed the hang: It seems sane to me - exit if there's a fatal signal, or doing core dump. Don't think there should be other conditions. > https://lore.kernel.org/lkml/[email protected]/ > > It was posted about a month ago and I don't see any response to it > on the lists... That's been a long discussion, but it's a different topic really. Yes it's signals, but it's not this particular issue. It'll happen to work around this issue, as it cancels everything post core dumping. -- Jens Axboe ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit 2021-09-21 21:41 ` Jens Axboe @ 2021-09-23 14:05 ` Olivier Langlois 0 siblings, 0 replies; 6+ messages in thread From: Olivier Langlois @ 2021-09-23 14:05 UTC (permalink / raw) To: Jens Axboe, Dave Chinner; +Cc: io-uring, linux-fsdevel On Tue, 2021-09-21 at 15:41 -0600, Jens Axboe wrote: > > > > Cleaned up so it compiles and the tests run properly again. But > > playing whack-a-mole with signals seems kinda fragile. I was > > pointed > > to this patchset by another dev on #xfs overnight who saw the same > > hangs that also fixed the hang: > > It seems sane to me - exit if there's a fatal signal, or doing core > dump. Don't think there should be other conditions. > > > https://lore.kernel.org/lkml/cover.1629655338.git.olivier@trillion0 > > 1.com/ > > > > It was posted about a month ago and I don't see any response to it > > on the lists... > > That's been a long discussion, but it's a different topic really. Yes > it's signals, but it's not this particular issue. It'll happen to > work > around this issue, as it cancels everything post core dumping. > I am glad to see that my patch is still on your radar. I was starting to wonder if it did somehow slip in a floor crack or if I did omit to do something justifying that noone is reviewing it. I guess that everyone has been crazy busy like mad men in the last few weeks... ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-09-23 14:05 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2021-09-21 6:40 [5.15-rc1 regression] io_uring: fsstress hangs in do_coredump() on exit Dave Chinner 2021-09-21 13:25 ` Jens Axboe 2021-09-21 14:19 ` Jens Axboe 2021-09-21 21:35 ` Dave Chinner 2021-09-21 21:41 ` Jens Axboe 2021-09-23 14:05 ` Olivier Langlois
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