diff options
| author | Sergey Senozhatsky <senozhatsky@chromium.org> | 2024-10-29 00:36:14 +0900 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-11-11 13:09:12 -0800 |
| commit | f85219096648b251a81e9fe24a1974590cfc417d (patch) | |
| tree | 444aca2660f87c00867001bcc4f8c16fe822347c | |
| parent | 408a8dc6232294ac83f233f869f425725765d2e1 (diff) | |
zram: clear IDLE flag after recompression
Patch series "zram: IDLE flag handling fixes", v2.
zram can wrongly preserve ZRAM_IDLE flag on its entries which can result
in premature post-processing (writeback and recompression) of such
entries.
This patch (of 2)
Recompression should clear ZRAM_IDLE flag on the entries it has accessed,
because otherwise some entries, specifically those for which recompression
has failed, become immediate candidate entries for another post-processing
(e.g. writeback).
Consider the following case:
- recompression marks entries IDLE every 4 hours and attempts
to recompress them
- some entries are incompressible, so we keep them intact and
hence preserve IDLE flag
- writeback marks entries IDLE every 8 hours and writebacks
IDLE entries, however we have IDLE entries left from
recompression, so writeback prematurely writebacks those
entries.
The bug was reported by Shin Kawamura.
Link: https://lkml.kernel.org/r/20241028153629.1479791-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20241028153629.1479791-2-senozhatsky@chromium.org
Fixes: 84b33bf78889 ("zram: introduce recompress sysfs knob")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reported-by: Shin Kawamura <kawasin@google.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index e6d12e81241d..a16dbffcdca3 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1864,6 +1864,13 @@ static int recompress_slot(struct zram *zram, u32 index, struct page *page, if (ret) return ret; + /* + * We touched this entry so mark it as non-IDLE. This makes sure that + * we don't preserve IDLE flag and don't incorrectly pick this entry + * for different post-processing type (e.g. writeback). + */ + zram_clear_flag(zram, index, ZRAM_IDLE); + class_index_old = zs_lookup_class_index(zram->mem_pool, comp_len_old); /* * Iterate the secondary comp algorithms list (in order of priority) |