From: Changwei Ge ge.changwei@h3c.com
[ Upstream commit 9e985787750db8aae87f02b67e908f28ac4d6b83 ]
When -EIOCBQUEUED returns, it means that aio_complete() will be called from dio_complete(), which is an asynchronous progress against write_iter. Generally, IO is a very slow progress than executing instruction, but we still can't take the risk to access a freed iocb.
And we do face a BUG crash issue. Using the crash tool, iocb is obviously freed already.
crash> struct -x kiocb ffff881a350f5900 struct kiocb { ki_filp = 0xffff881a350f5a80, ki_pos = 0x0, ki_complete = 0x0, private = 0x0, ki_flags = 0x0 }
And the backtrace shows: ocfs2_file_write_iter+0xcaa/0xd00 [ocfs2] aio_run_iocb+0x229/0x2f0 do_io_submit+0x291/0x540 SyS_io_submit+0x10/0x20 system_call_fastpath+0x16/0x75
Link: http://lkml.kernel.org/r/1523361653-14439-1-git-send-email-ge.changwei@h3c.c... Signed-off-by: Changwei Ge ge.changwei@h3c.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Joseph Qi jiangqi903@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ocfs2/file.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c index a847fe52c56ee..a3e077fcfeb9b 100644 --- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -2389,7 +2389,7 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
written = __generic_file_write_iter(iocb, from); /* buffered aio wouldn't have proper lock coverage today */ - BUG_ON(written == -EIOCBQUEUED && !(iocb->ki_flags & IOCB_DIRECT)); + BUG_ON(written == -EIOCBQUEUED && !direct_io);
/* * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io @@ -2509,7 +2509,7 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb, trace_generic_file_read_iter_ret(ret);
/* buffered aio wouldn't have proper lock coverage today */ - BUG_ON(ret == -EIOCBQUEUED && !(iocb->ki_flags & IOCB_DIRECT)); + BUG_ON(ret == -EIOCBQUEUED && !direct_io);
/* see ocfs2_file_write_iter */ if (ret == -EIOCBQUEUED || !ocfs2_iocb_is_rw_locked(iocb)) {