[PATCH] mm: swap write failure fixup (6ddab3b9) · Commits · 戴 / test

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>

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);
		}

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