On Mon, Nov 11, 2024 at 8:42 AM Brian Geffon <bgeffon@xxxxxxxxxx> wrote: > > 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 > > > >
