mm: never attempt async page lock if we've transferred data already (0abed7c6) · Commits · 戴 / test

We catch the case where we enter generic_file_buffered_read() with data already transferred, but we also need to be careful not to allow an async page lock if we're looping transferring data. If not, we could be returning -EIOCBQUEUED instead of the transferred amount, and it could result in double waitqueue additions as well. Cc: stable@vger.kernel.org # v5.9 Fixes: ("mm: support async buffered reads in generic_file_buffered_read()") Signed-off-by:

Jens Axboe <axboe@kernel.dk>

mm/filemap.c

+14 −4

Original line number	Diff line number	Diff line
		@@ -2347,10 +2347,15 @@ page_ok:

		page_not_up_to_date:
		/* Get exclusive access to the page ... */
		if (iocb->ki_flags & IOCB_WAITQ)
		if (iocb->ki_flags & IOCB_WAITQ) {
		if (written) {
		put_page(page);
		goto out;
		}
		error = lock_page_async(page, iocb->ki_waitq);
		else
		} else {
		error = lock_page_killable(page);
		}
		if (unlikely(error))
		goto readpage_error;

		@@ -2393,10 +2398,15 @@ readpage:
		}

		if (!PageUptodate(page)) {
		if (iocb->ki_flags & IOCB_WAITQ)
		if (iocb->ki_flags & IOCB_WAITQ) {
		if (written) {
		put_page(page);
		goto out;
		}
		error = lock_page_async(page, iocb->ki_waitq);
		else
		} else {
		error = lock_page_killable(page);
		}

		if (unlikely(error))
		goto readpage_error;

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