From: Pavel Begunkov asml.silence@gmail.com
Upstream commits:
8eb06d7e8dd85 ("io_uring: fix missing ->mm on exit") cbcf72148da4a ("io_uring: return locked and pinned page accounting")
do_exit() first drops current->mm and then runs task_work, from where io_sq_thread_acquire_mm() would try to set mm for a user dying process.
[ 208.004249] WARNING: CPU: 2 PID: 1854 at kernel/kthread.c:1238 kthread_use_mm+0x244/0x270 [ 208.004287] kthread_use_mm+0x244/0x270 [ 208.004288] io_sq_thread_acquire_mm.part.0+0x54/0x80 [ 208.004290] io_async_task_func+0x258/0x2ac [ 208.004291] task_work_run+0xc8/0x210 [ 208.004294] do_exit+0x1b8/0x430 [ 208.004295] do_group_exit+0x44/0xac [ 208.004296] get_signal+0x164/0x69c [ 208.004298] do_signal+0x94/0x1d0 [ 208.004299] do_notify_resume+0x18c/0x340 [ 208.004300] work_pending+0x8/0x3d4
Reported-by: Roman Gershman romange@gmail.com Tested-by: Roman Gershman romange@gmail.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/io_uring.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4363,7 +4363,8 @@ static int io_sq_thread_acquire_mm(struc struct io_kiocb *req) { if (io_op_defs[req->opcode].needs_mm && !current->mm) { - if (unlikely(!mmget_not_zero(ctx->sqo_mm))) + if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL) || + !mmget_not_zero(ctx->sqo_mm))) return -EFAULT; kthread_use_mm(ctx->sqo_mm); }