Commit c153b494 authored by Weijie Yang's avatar Weijie Yang Committed by Luis Henriques

mm: frontswap: invalidate expired data on a dup-store failure

commit fb993fa1 upstream.

If a frontswap dup-store failed, it should invalidate the expired page
in the backend, or it could trigger some data corruption issue.
Such as:
 1. use zswap as the frontswap backend with writeback feature
 2. store a swap page(version_1) to entry A, success
 3. dup-store a newer page(version_2) to the same entry A, fail
 4. use __swap_writepage() write version_2 page to swapfile, success
 5. zswap do shrink, writeback version_1 page to swapfile
 6. version_2 page is overwrited by version_1, data corrupt.

This patch fixes this issue by invalidating expired data immediately
when meet a dup-store failure.
Signed-off-by: default avatarWeijie Yang <weijie.yang@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Bob Liu <bob.liu@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 5293a688
...@@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) ...@@ -244,8 +244,10 @@ int __frontswap_store(struct page *page)
the (older) page from frontswap the (older) page from frontswap
*/ */
inc_frontswap_failed_stores(); inc_frontswap_failed_stores();
if (dup) if (dup) {
__frontswap_clear(sis, offset); __frontswap_clear(sis, offset);
frontswap_ops->invalidate_page(type, offset);
}
} }
if (frontswap_writethrough_enabled) if (frontswap_writethrough_enabled)
/* report failure so swap also writes to swap device */ /* report failure so swap also writes to swap device */
......
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