From fb993fa1a2f669215fa03a09eed7848f2663e336 Mon Sep 17 00:00:00 2001 From: Weijie Yang Date: Tue, 2 Dec 2014 15:59:25 -0800 Subject: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure 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: Weijie Yang Cc: Konrad Rzeszutek Wilk Cc: Seth Jennings Cc: Dan Streetman Cc: Minchan Kim Cc: Bob Liu Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/frontswap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/frontswap.c b/mm/frontswap.c index c30eec536f03..f2a3571c6e22 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) the (older) page from frontswap */ inc_frontswap_failed_stores(); - if (dup) + if (dup) { __frontswap_clear(sis, offset); + frontswap_ops->invalidate_page(type, offset); + } } if (frontswap_writethrough_enabled) /* report failure so swap also writes to swap device */ -- 2.20.1