From 0abed7c69b956d135cb6d320c350b2adb213e7d8 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 16 Nov 2020 13:36:24 -0700 Subject: [PATCH] mm: never attempt async page lock if we've transferred data already 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: 1a0a7853b901 ("mm: support async buffered reads in generic_file_buffered_read()") Signed-off-by: Jens Axboe --- mm/filemap.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index d5e7c2029d16..3ebbe64a0106 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -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;