The patch titled
Subject: drivers/block/zram/zram_drv.c: do not keep dangling zcomp pointer after zram reset
has been added to the -mm mm-unstable branch. Its filename is
block-zram-do-not-keep-dangling-zcomp-pointer-after-zram-reset.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/block-zram-do-not-keep-dangling-zcomp-pointer-after-zram-reset.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: drivers/block/zram/zram_drv.c: do not keep dangling zcomp pointer after zram reset
Date: Wed, 24 Aug 2022 12:51:00 +0900
We do all reset operations under write lock, so we don't need to save
->disksize and ->comp to stack variables. Another thing is that ->comp is
freed during zram reset, but comp pointer is not NULL-ed, so zram keeps
the freed pointer value.
Link: https://lkml.kernel.org/r/20220824035100.971816-1-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
--- a/drivers/block/zram/zram_drv.c~block-zram-do-not-keep-dangling-zcomp-pointer-after-zram-reset
+++ a/drivers/block/zram/zram_drv.c
@@ -1689,9 +1689,6 @@ out:
static void zram_reset_device(struct zram *zram)
{
- struct zcomp *comp;
- u64 disksize;
-
down_write(&zram->init_lock);
zram->limit_pages = 0;
@@ -1701,17 +1698,15 @@ static void zram_reset_device(struct zra
return;
}
- comp = zram->comp;
- disksize = zram->disksize;
- zram->disksize = 0;
-
set_capacity_and_notify(zram->disk, 0);
part_stat_set_all(zram->disk->part0, 0);
/* I/O operation under all of CPU are done so let's free */
- zram_meta_free(zram, disksize);
+ zram_meta_free(zram, zram->disksize);
+ zram->disksize = 0;
memset(&zram->stats, 0, sizeof(zram->stats));
- zcomp_destroy(comp);
+ zcomp_destroy(zram->comp);
+ zram->comp = NULL;
reset_bdev(zram);
up_write(&zram->init_lock);
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
mm-zsmalloc-do-not-attempt-to-free-is_err-handle.patch
block-zram-do-not-keep-dangling-zcomp-pointer-after-zram-reset.patch
