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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2006-09-26 06:31:26 (GMT)
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-26 15:48:48 (GMT)
commit6ddab3b9ebebc88bfdd8107c64f12d7e4480c559 (patch)
tree192edd3a85d3665bb7e44c429609a7357ba12bac /mm/page_io.c
parentca5f9703dffa012cc46166e6206c5a992910e041 (diff)
[PATCH] mm: swap write failure fixup
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. [akpm@osdl.org: printk warning fix] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/page_io.c')
-rw-r--r--mm/page_io.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/mm/page_io.c b/mm/page_io.c
index 8802994..d2f0a57 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -52,8 +52,23 @@ static int end_swap_bio_write(struct bio *bio, unsigned int bytes_done, int err)
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 (%u:%u:%Lu)\n",
+ imajor(bio->bi_bdev->bd_inode),
+ iminor(bio->bi_bdev->bd_inode),
+ (unsigned long long)bio->bi_sector);
+ ClearPageReclaim(page);
+ }
end_page_writeback(page);
bio_put(bio);
return 0;
@@ -70,6 +85,10 @@ static int end_swap_bio_read(struct bio *bio, unsigned int bytes_done, int err)
if (!uptodate) {
SetPageError(page);
ClearPageUptodate(page);
+ printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
+ imajor(bio->bi_bdev->bd_inode),
+ iminor(bio->bi_bdev->bd_inode),
+ (unsigned long long)bio->bi_sector);
} else {
SetPageUptodate(page);
}

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