diff options
| author | Jens Axboe <axboe@kernel.dk> | 2020-05-26 09:38:31 -0600 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-05-26 18:34:58 +0200 |
| commit | 18f855e574d9799a0e7489f8ae6fd8447d0dd74a (patch) | |
| tree | 405cfc649570919e8cc52a27db30e27b064ddb88 /kernel/sched/fair.c | |
| parent | 39f23ce07b9355d05a64ae303ce20d1c4b92b957 (diff) | |
sched/fair: Don't NUMA balance for kthreads
Stefano reported a crash with using SQPOLL with io_uring:
BUG: kernel NULL pointer dereference, address: 00000000000003b0
CPU: 2 PID: 1307 Comm: io_uring-sq Not tainted 5.7.0-rc7 #11
RIP: 0010:task_numa_work+0x4f/0x2c0
Call Trace:
task_work_run+0x68/0xa0
io_sq_thread+0x252/0x3d0
kthread+0xf9/0x130
ret_from_fork+0x35/0x40
which is task_numa_work() oopsing on current->mm being NULL.
The task work is queued by task_tick_numa(), which checks if current->mm is
NULL at the time of the call. But this state isn't necessarily persistent,
if the kthread is using use_mm() to temporarily adopt the mm of a task.
Change the task_tick_numa() check to exclude kernel threads in general,
as it doesn't make sense to attempt ot balance for kthreads anyway.
Reported-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/865de121-8190-5d30-ece5-3b097dc74431@kernel.dk
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 538ba5d94e99..da3e5b54715b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2908,7 +2908,7 @@ static void task_tick_numa(struct rq *rq, struct task_struct *curr) /* * We don't care about NUMA placement if we don't have memory. */ - if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) + if ((curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work) return; /* |