From: NeilBrown <neilb@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>,
Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
"Darrick J. Wong" <djwong@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.com>,
". Dave Chinner" <david@fromorbit.com>,
Jonathan Corbet <corbet@lwn.net>
Cc: linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org
Subject: [PATCH 6/6] XFS: remove congestion_wait() loop from xfs_buf_alloc_pages()
Date: Fri, 17 Sep 2021 12:56:57 +1000 [thread overview]
Message-ID: <163184741782.29351.3052773526186670351.stgit@noble.brown> (raw)
In-Reply-To: <163184698512.29351.4735492251524335974.stgit@noble.brown>
Documentation commment in gfp.h discourages indefinite retry loops on
ENOMEM and says of __GFP_NOFAIL that it
is definitely preferable to use the flag rather than opencode
endless loop around allocator.
congestion_wait() is indistinguishable from
schedule_timeout_uninterruptible() in practice and it is not a good way
to wait for memory to become available.
So add __GFP_NOFAIL to gfp if failure is not an option, and remove the
congestion_wait(). We now only loop when failure is an option, and
alloc_bulk_pages_array() made some progres, but not enough.
Signed-off-by: NeilBrown <neilb@suse.de>
---
fs/xfs/xfs_buf.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 5fa6cd947dd4..b19ab52c551b 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -352,7 +352,7 @@ xfs_buf_alloc_pages(
if (flags & XBF_READ_AHEAD)
gfp_mask |= __GFP_NORETRY;
else
- gfp_mask |= GFP_NOFS;
+ gfp_mask |= GFP_NOFS | __GFP_NOFAIL;
/* Make sure that we have a page list */
bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
@@ -372,8 +372,9 @@ xfs_buf_alloc_pages(
/*
* Bulk filling of pages can take multiple calls. Not filling the entire
- * array is not an allocation failure, so don't back off if we get at
- * least one extra page.
+ * array is not an allocation failure but is worth counting in
+ * xb_pages_retries statistics. If we don't even get one page,
+ * then this must be a READ_AHEAD and we should abort.
*/
for (;;) {
long last = filled;
@@ -385,16 +386,13 @@ xfs_buf_alloc_pages(
break;
}
- if (filled != last)
- continue;
-
- if (flags & XBF_READ_AHEAD) {
+ if (filled == last) {
+ ASSERT(flags & XBF_READ_AHEAD);
xfs_buf_free_pages(bp);
return -ENOMEM;
}
XFS_STATS_INC(bp->b_mount, xb_page_retries);
- congestion_wait(BLK_RW_ASYNC, HZ / 50);
}
return 0;
}
next prev parent reply other threads:[~2021-09-17 3:00 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-17 2:56 [PATCH 0/6 v2] congestion_wait() and GFP_NOFAIL NeilBrown
2021-09-17 2:56 ` NeilBrown [this message]
2021-09-17 2:56 ` [PATCH 5/6] XFS: remove congestion_wait() loop from kmem_alloc() NeilBrown
2021-09-17 21:45 ` Dave Chinner
2021-09-17 2:56 ` [PATCH 1/6] MM: Support __GFP_NOFAIL in alloc_pages_bulk_*() and improve doco NeilBrown
2021-09-17 14:42 ` Mel Gorman
2021-09-20 23:48 ` NeilBrown
2021-10-05 9:16 ` Vlastimil Babka
2021-09-17 2:56 ` [PATCH 3/6] EXT4: Remove ENOMEM/congestion_wait() loops NeilBrown
2021-09-17 2:56 ` [PATCH 4/6] EXT4: remove congestion_wait from ext4_bio_write_page, and simplify NeilBrown
2021-09-17 2:56 ` [PATCH 2/6] MM: improve documentation for __GFP_NOFAIL NeilBrown
2021-10-05 9:20 ` Vlastimil Babka
2021-10-05 11:09 ` Michal Hocko
2021-10-05 12:27 ` Vlastimil Babka
2021-10-06 23:14 ` Dave Chinner
2021-10-07 10:07 ` Michal Hocko
2021-10-07 23:15 ` NeilBrown
2021-10-08 7:48 ` Michal Hocko
2021-10-08 22:36 ` Dave Chinner
2021-10-11 11:57 ` Michal Hocko
2021-10-11 21:49 ` NeilBrown
2021-10-18 10:23 ` Michal Hocko
2021-10-19 4:32 ` NeilBrown
2021-10-19 13:59 ` Michal Hocko
2021-10-22 0:09 ` NeilBrown
2021-10-13 2:32 ` Dave Chinner
2021-10-13 8:26 ` Michal Hocko
2021-10-14 11:32 ` David Sterba
2021-10-14 11:46 ` Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2021-09-14 0:13 [PATCH 0/6] congestion_wait() and GFP_NOFAIL NeilBrown
2021-09-14 0:13 ` [PATCH 6/6] XFS: remove congestion_wait() loop from xfs_buf_alloc_pages() NeilBrown
2021-09-14 2:08 ` Dave Chinner
2021-09-14 2:35 ` NeilBrown
2021-09-14 5:33 ` Dave Chinner
2021-09-14 16:45 ` Mel Gorman
2021-09-14 21:13 ` NeilBrown
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