On 2021/9/1 下午5:47, Pavel Begunkov wrote: > On 9/1/21 10:39 AM, 王贇 wrote: >> We observed panic: >> BUG: kernel NULL pointer dereference, address:0000000000000028 >> [skip] >> Oops: 0000 [#1] SMP PTI >> CPU: 1 PID: 737 Comm: a.out Not tainted 5.14.0+ #58 >> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 >> RIP: 0010:vfs_fadvise+0x1e/0x80 >> [skip] >> Call Trace: >> ? tctx_task_work+0x111/0x2a0 >> io_issue_sqe+0x524/0x1b90 > > Most likely it was fixed yesterday. Can you try? > https://git.kernel.dk/cgit/linux-block/log/?h=for-5.15/io_uring > > Or these two patches in particular > > https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=c6d3d9cbd659de8f2176b4e4721149c88ac096d4 > https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=b8ce1b9d25ccf81e1bbabd45b963ed98b2222df8 Yup, it no longer panic :-) Regards, Michael Wang > >> This is caused by io_wq_submit_work() calling io_issue_sqe() >> on a failed fadvise request, and the io_init_req() return error >> before initialize the file for it, lead into the panic when >> vfs_fadvise() try to access 'req->file'. >> >> This patch add the missing check & handle for failed request >> before calling io_issue_sqe(). >> >> Signed-off-by: Michael Wang <yun.wang@xxxxxxxxxxxxxxxxx> >> --- >> fs/io_uring.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 6f35b12..bfec7bf 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -2214,7 +2214,8 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked) >> >> io_tw_lock(ctx, locked); >> /* req->task == current here, checking PF_EXITING is safe */ >> - if (likely(!(req->task->flags & PF_EXITING))) >> + if (likely(!(req->task->flags & PF_EXITING) && >> + !(req->flags & REQ_F_FAIL))) >> __io_queue_sqe(req); >> else >> io_req_complete_failed(req, -EFAULT); >> @@ -6704,7 +6705,10 @@ static void io_wq_submit_work(struct io_wq_work *work) >> >> if (!ret) { >> do { >> - ret = io_issue_sqe(req, 0); >> + if (likely(!(req->flags & REQ_F_FAIL))) >> + ret = io_issue_sqe(req, 0); >> + else >> + io_req_complete_failed(req, -EFAULT); >> /* >> * We can get EAGAIN for polled IO even though we're >> * forcing a sync submission from here, since we can't >> >
