cpuset: Fix memory allocator deadlock
PATCH 1/1 cpuset: Fix memory allocator deadlock
Juri hit the below lockdep report:
[ 4.303391] ======================================================
[ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ]
[ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted
[ 4.303395] ------------------------------------------------------
[ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290
[ 4.303417]
[ 4.303417] and this task is already holding:
[ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100
[ 4.303431] which would create a new lock dependency:
[ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...}
[ 4.303436][ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock:
[ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 {
[ 4.303922] HARDIRQ-ON-W at:
[ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0
[ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140
[ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180
[ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0
[ 4.303933] SOFTIRQ-ON-W at:
[ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0
[ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140
[ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180
[ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0
[ 4.303959] INITIAL USE at:
[ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0
[ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140
[ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180
[ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0
[ 4.303972] }Which reports that we take mems_allowed_seq with interrupts enabled. A little digging found that this can only be from cpuset_change_task_nodemask().
This is an actual deadlock because an interrupt doing an allocation will hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin forever waiting for the write side to complete.
Cc John Stultz <[email protected]>
Cc Mel Gorman <[email protected]>
Reported-by Juri Lelli <[email protected]>
Signed-off-by Peter Zijlstra <[email protected]>
--- kernel/cpuset.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
kernel/cpuset.c +6 -2
@@ -1033,8 +1033,10 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk, need_loop =task_has_mempolicy (tsk) || !nodes_intersects (*newmems, tsk->mems_allowed); -if (need_loop) +if (need_loop) { +local_irq_disable ();write_seqcount_begin (&tsk->mems_allowed_seq); + }nodes_or (tsk->mems_allowed, tsk->mems_allowed, *newmems);mpol_rebind_task (tsk, newmems,MPOL_REBIND_STEP1 );
@@ -1042,8 +1044,10 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,mpol_rebind_task (tsk, newmems,MPOL_REBIND_STEP2 ); tsk->mems_allowed = *newmems; -if (need_loop) +if (need_loop) {write_seqcount_end (&tsk->mems_allowed_seq); +local_irq_enable (); + }task_unlock (tsk); }
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Quoted 34 lines · Peter Zijlstra
Juri hit the below lockdep report:
[ 4.303391] ====================================================== [ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ] [ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted [ 4.303395] ------------------------------------------------------ [ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290 [ 4.303417] [ 4.303417] and this task is already holding: [ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100 [ 4.303431] which would create a new lock dependency: [ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...} [ 4.303436][ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: [ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 { [ 4.303922] HARDIRQ-ON-W at: [ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0 [ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303933] SOFTIRQ-ON-W at: [ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0 [ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303959] INITIAL USE at: [ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0 [ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303972] }
Quoted 8 lines
Which reports that we take
mems_allowed_seqwith interrupts enabled. A little digging found that this can only be fromcpuset_change_task_nodemask().This is an actual deadlock because an interrupt doing an allocation will hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin forever waiting for the write side to complete.
And this patch fixes it, thanks!
Quoted 4 lines
Cc John Stultz <[email protected]>Cc Mel Gorman <[email protected]>Reported-by Juri Lelli <[email protected]>Signed-off-by Peter Zijlstra <[email protected]>
Tested-by Juri Lelli <[email protected]>
Best,
- Juri
Quoted 23 lines
--- kernel/cpuset.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)kernel/cpuset.c +3
-1@@ -1033,8 +1033,10 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk, need_loop =task_has_mempolicy (tsk) || !nodes_intersects (*newmems, tsk->mems_allowed); -if (need_loop) +if (need_loop) { +local_irq_disable ();write_seqcount_begin (&tsk->mems_allowed_seq); + }nodes_or (tsk->mems_allowed, tsk->mems_allowed, *newmems);mpol_rebind_task (tsk, newmems,MPOL_REBIND_STEP1 );@@ -1042,8 +1044,10 @@ static void cpuset_change_task_nodemask(struct task_struct *tsk,mpol_rebind_task (tsk, newmems,MPOL_REBIND_STEP2 );
kernel/cpuset.c static void cpuset_change_task_nodemask(struct task_struct *tsk, · line 1053
Quoted 10 lines
kernel/cpuset.c +3
-1tsk->mems_allowed = *newmems; -if (need_loop) +if (need_loop) {write_seqcount_end (&tsk->mems_allowed_seq); +local_irq_enable (); + }task_unlock (tsk); }
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Quoted 34 lines · Peter Zijlstra
Juri hit the below lockdep report:
[ 4.303391] ====================================================== [ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ] [ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted [ 4.303395] ------------------------------------------------------ [ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290 [ 4.303417] [ 4.303417] and this task is already holding: [ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100 [ 4.303431] which would create a new lock dependency: [ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...} [ 4.303436][ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: [ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 { [ 4.303922] HARDIRQ-ON-W at: [ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0 [ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303933] SOFTIRQ-ON-W at: [ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0 [ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303959] INITIAL USE at: [ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0 [ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303972] }
Quoted 4 lines
Which reports that we take
mems_allowed_seqwith interrupts enabled. A little digging found that this can only be fromcpuset_change_task_nodemask().
Yeah, the other one in set_mems_allowed() was fixed by John.
Quoted 8 lines
This is an actual deadlock because an interrupt doing an allocation will hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin forever waiting for the write side to complete.
Cc John Stultz <[email protected]>Cc Mel Gorman <[email protected]>Reported-by Juri Lelli <[email protected]>Signed-off-by Peter Zijlstra <[email protected]>
Acked-by Li Zefan <[email protected]>
Quoted 38 lines · Peter Zijlstra
Juri hit the below lockdep report:
[ 4.303391] ====================================================== [ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ] [ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted [ 4.303395] ------------------------------------------------------ [ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290 [ 4.303417] [ 4.303417] and this task is already holding: [ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100 [ 4.303431] which would create a new lock dependency: [ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...} [ 4.303436][ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: [ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 { [ 4.303922] HARDIRQ-ON-W at: [ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0 [ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303933] SOFTIRQ-ON-W at: [ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0 [ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303959] INITIAL USE at: [ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0 [ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303972] }Which reports that we take
mems_allowed_seqwith interrupts enabled. A little digging found that this can only be fromcpuset_change_task_nodemask().
Quoted 8 lines
This is an actual deadlock because an interrupt doing an allocation will hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin forever waiting for the write side to complete.
Cc John Stultz <[email protected]>Cc Mel Gorman <[email protected]>Reported-by Juri Lelli <[email protected]>Signed-off-by Peter Zijlstra <[email protected]>
Acked-by Mel Gorman <[email protected]>
Signature · 8 lines
Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
Tejun Heo
AppliedQuoted 38 lines · Peter Zijlstra
Juri hit the below lockdep report:
[ 4.303391] ====================================================== [ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ] [ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted [ 4.303395] ------------------------------------------------------ [ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290 [ 4.303417] [ 4.303417] and this task is already holding: [ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100 [ 4.303431] which would create a new lock dependency: [ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...} [ 4.303436][ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: [ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 { [ 4.303922] HARDIRQ-ON-W at: [ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0 [ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303933] SOFTIRQ-ON-W at: [ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0 [ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303959] INITIAL USE at: [ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0 [ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303972] }Which reports that we take
mems_allowed_seqwith interrupts enabled. A little digging found that this can only be fromcpuset_change_task_nodemask().
Quoted 8 lines
This is an actual deadlock because an interrupt doing an allocation will hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin forever waiting for the write side to complete.
Cc John Stultz <[email protected]>Cc Mel Gorman <[email protected]>Reported-by Juri Lelli <[email protected]>Signed-off-by Peter Zijlstra <[email protected]>
Applied to cgroup/for-3.13-fixes w/ stable cc'd.
Thanks.
Signature · 7 lines
tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"[email protected]"> [email protected] </a>