On Mon, Nov 11, 2024 at 3:28 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > The quilt patch titled > Subject: zram: clear IDLE flag after recompression > has been removed from the -mm tree. Its filename was > zram-clear-idle-flag-after-recompression.patch > > This patch was dropped because it was merged into the mm-stable branch > of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm > > ------------------------------------------------------ > From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> > Subject: zram: clear IDLE flag after recompression > Date: Tue, 29 Oct 2024 00:36:14 +0900 > > 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@xxxxxxxxxxxx > Link: https://lkml.kernel.org/r/20241028153629.1479791-2-senozhatsky@xxxxxxxxxxxx > Fixes: 84b33bf78889 ("zram: introduce recompress sysfs knob") > Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> > Reported-by: Shin Kawamura <kawasin@xxxxxxxxxx> > Acked-by: Brian Geffon <bgeffon@xxxxxxxxxx> > Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > drivers/block/zram/zram_drv.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > --- a/drivers/block/zram/zram_drv.c~zram-clear-idle-flag-after-recompression > +++ a/drivers/block/zram/zram_drv.c > @@ -1864,6 +1864,13 @@ static int recompress_slot(struct zram * > 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) > _ > > Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are > >
