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Commit 6ddab3b9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds
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[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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ca5f9703

mm/page_io.c

+20 −1
Original line number Diff line number Diff line
@@ -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);

	}