two 5.8 fixes
cover two 5.8 fixes
[2/2] is actually fixed in 5.9, but apparently it wasn't just a speculation but rather an actual issue. It fixes locally, by moving put out of lock, because don't see a reason why it's there.
Pavel Begunkov (2):
io_uring: fix ->work corruption with poll_add
io_uring: fix lockup in io_fail_links()
fs/io_uring.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
Signature · 1 line
2.24.0
PATCH 1/2 io_uring: fix ->work corruption with poll_add
req->work might be already initialised by the time it gets into __io_arm_poll_handler(), which will corrupt it be using fields that are in an union with req->work. Luckily, the only side effect is missing put_creds(). Clean req->work before going there.
--- fs/io_uring.c | 4 ++++ 1 file changed, 4 insertions(+)
fs/io_uring.c +4 -0
@@ -4658,6 +4658,10 @@ static int io_poll_add(struct io_kiocb *req)struct io_poll_table ipt;__poll_t mask; +/* ->work is in union with hash_node and others */ +io_req_work_drop_env (req); + req->flags &= ~REQ_F_WORK_INITIALIZED ; +INIT_HLIST_NODE (&req->hash_node);INIT_LIST_HEAD (&req->list); ipt.pt._qproc = io_poll_queue_proc;
Signature · 1 line
2.24.0
Re: [PATCH 1/2] io_uring: fix ->work corruption with poll_add
Quoted 2 lines · Pavel Begunkov
req->workmight be already initialised by the time it gets into__io_arm_poll_handler(), which will corrupt it be using fields that are
s/be using/by using/
Jens, could you please fold it in, if the patch would do? Or let me know and I'll resend.
Quoted 25 lines
in an union with
req->work. Luckily, the only side effect is missingput_creds(). Cleanreq->workbefore going there.Suggested-by Jens Axboe <[email protected]>Signed-off-by Pavel Begunkov <[email protected]>--- fs/io_uring.c | 4 ++++ 1 file changed, 4 insertions(+)fs/io_uring.c +4
-0@@ -4658,6 +4658,10 @@ static int io_poll_add(struct io_kiocb *req)struct io_poll_table ipt;__poll_t mask; +/* ->work is in union with hash_node and others */ +io_req_work_drop_env (req); + req->flags &= ~REQ_F_WORK_INITIALIZED ; +INIT_HLIST_NODE (&req->hash_node);INIT_LIST_HEAD (&req->list); ipt.pt._qproc = io_poll_queue_proc;
Signature · 1 line
Pavel Begunkov
PATCH 2/2 io_uring: fix lockup in io_fail_links()
In reply to Pavel Begunkovio_fail_links() doesn't consider REQ_F_COMP_LOCKED leading to nested spin_lock(completion_lock) and lockup.
[ 197.680409] rcu: INFO: rcu_preempt detected expedited stalls on
CPUs/tasks: { 6-... } 18239 jiffies s: 1421 root: 0x40/.
[ 197.680411] rcu: blocking rcu_node structures:
[ 197.680412] Task dump for CPU 6:
[ 197.680413] link-timeout R running task 0 1669
1 0x8000008a
[ 197.680414] Call Trace:
[ 197.680420] ? io_req_find_next+0xa0/0x200
[ 197.680422] ? io_put_req_find_next+0x2a/0x50
[ 197.680423] ? io_poll_task_func+0xcf/0x140
[ 197.680425] ? task_work_run+0x67/0xa0
[ 197.680426] ? do_exit+0x35d/0xb70
[ 197.680429] ? syscall_trace_enter+0x187/0x2c0
[ 197.680430] ? do_group_exit+0x43/0xa0
[ 197.680448] ? __x64_sys_exit_group+0x18/0x20
[ 197.680450] ? do_syscall_64+0x52/0xa0
[ 197.680452] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9--- fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
fs/io_uring.c +1 -2
@@ -4199,10 +4199,9 @@ static void io_poll_task_handler(struct io_kiocb *req, struct io_kiocb **nxt)hash_del (&req->hash_node);io_poll_complete (req, req->result,0 ); - req->flags |=REQ_F_COMP_LOCKED ; -io_put_req_find_next (req, nxt);spin_unlock_irq (&ctx->completion_lock); +io_put_req_find_next (req, nxt);io_cqring_ev_posted (ctx); }
Signature · 1 line
2.24.0
Jens Axboe
maintainerQuoted 3 lines · Pavel Begunkov
[2/2] is actually fixed in 5.9, but apparently it wasn't just a speculation but rather an actual issue. It fixes locally, by moving put out of lock, because don't see a reason why it's there.
Thanks, I applied with the fixed spelling, and shuffled things around a bit.
Signature · 1 line
Jens Axboe