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authorXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>2020-12-18 15:26:48 +0800
committerJens Axboe <axboe@kernel.dk>2020-12-18 08:15:10 -0700
commit0020ef04e48571a88d4f482ad08f71052c5c5a08 (patch)
tree44fb4bc38dff63a4e18f499cb99a6e153a8c2a47 /fs/io-wq.h
parent89448c47b8452b67c146dc6cad6f737e004c5caf (diff)
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io_uring: fix io_wqe->work_list corruption
For the first time a req punted to io-wq, we'll initialize io_wq_work's list to be NULL, then insert req to io_wqe->work_list. If this req is not inserted into tail of io_wqe->work_list, this req's io_wq_work list will point to another req's io_wq_work. For splitted bio case, this req maybe inserted to io_wqe->work_list repeatedly, once we insert it to tail of io_wqe->work_list for the second time, now io_wq_work->list->next will be invalid pointer, which then result in many strang error, panic, kernel soft-lockup, rcu stall, etc. In my vm, kernel doest not have commit cc29e1bf0d63f7 ("block: disable iopoll for split bio"), below fio job can reproduce this bug steadily: [global] name=iouring-sqpoll-iopoll-1 ioengine=io_uring iodepth=128 numjobs=1 thread rw=randread direct=1 registerfiles=1 hipri=1 bs=4m size=100M runtime=120 time_based group_reporting randrepeat=0 [device] directory=/home/feiman.wxg/mntpoint/ # an ext4 mount point If we have commit cc29e1bf0d63f7 ("block: disable iopoll for split bio"), there will no splitted bio case for polled io, but I think we still to need to fix this list corruption, it also should maybe go to stable branchs. To fix this corruption, if a req is inserted into tail of io_wqe->work_list, initialize req->io_wq_work->list->next to bu NULL. Cc: stable@vger.kernel.org Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io-wq.h')
-rw-r--r--fs/io-wq.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/io-wq.h b/fs/io-wq.h
index 069496c6d4f9..75113bcd5889 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -59,6 +59,7 @@ static inline void wq_list_add_tail(struct io_wq_work_node *node,
list->last->next = node;
list->last = node;
}
+ node->next = NULL;
}
static inline void wq_list_cut(struct io_wq_work_list *list,