The patch titled
mm: swap write failure fixup
has been added to the -mm tree. Its filename is
mm-swap-write-failure-fixup.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: mm: swap write failure fixup
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Currently we can silently drop data if the write to swap failed. It
usually doesn't result in data-corruption because on page-in the process
will receive SIGBUS (assuming write-failure implies read-failure).
This assumption might or might not be valid.
This patch will avoid the page being discarded after a failed write. But
will print a warning the sysadmin _should_ take to heart, if a lot of swap
space becomes un-writeable, OOM is not far off.
Tested by making the write fail 'randomly' once every 50 writes or so.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/page_io.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff -puN mm/page_io.c~mm-swap-write-failure-fixup mm/page_io.c
--- a/mm/page_io.c~mm-swap-write-failure-fixup
+++ a/mm/page_io.c
@@ -52,8 +52,22 @@ static int end_swap_bio_write(struct bio
if (bio->bi_size)
return 1;
- if (!uptodate)
+ if (!uptodate) {
SetPageError(page);
+ /*
+ * We failed to write the page out to swap-space.
+ * Re-dirty the page in order to avoid it being reclaimed.
+ * Also print a dire warning that things will go BAD (tm)
+ * very quickly.
+ *
+ * Also clear PG_reclaim to avoid rotate_reclaimable_page()
+ */
+ set_page_dirty(page);
+ printk(KERN_ALERT "Write-error on swap-device (%d:%d)\n",
+ imajor(bio->bi_bdev->bd_inode),
+ iminor(bio->bi_bdev->bd_inode));
+ ClearPageReclaim(page);
+ }
end_page_writeback(page);
bio_put(bio);
return 0;
_
Patches currently in -mm which might be from a.p.zijlstra@xxxxxxxxx are
mm-tracking-shared-dirty-pages.patch
mm-balance-dirty-pages.patch
mm-optimize-the-new-mprotect-code-a-bit.patch
mm-small-cleanup-of-install_page.patch
mm-fixup-do_wp_page.patch
mm-msync-cleanup.patch
mm-tracking-shared-dirty-pages-checks.patch
mm-tracking-shared-dirty-pages-wimp.patch
mm-swap-write-failure-fixup.patch
-
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