This is a note to let you know that I've just added the patch titled
zram: fix broken page writeback
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-fix-broken-page-writeback.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2766f1821600cc7562bae2128ad0b163f744c5d9 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@xxxxxxxxxx>
Date: Fri, 12 Mar 2021 21:08:41 -0800
Subject: zram: fix broken page writeback
From: Minchan Kim <minchan@xxxxxxxxxx>
commit 2766f1821600cc7562bae2128ad0b163f744c5d9 upstream.
commit 0d8359620d9b ("zram: support page writeback") introduced two
problems. It overwrites writeback_store's return value as kstrtol's
return value, which makes return value zero so user could see zero as
return value of write syscall even though it wrote data successfully.
It also breaks index value in the loop in that it doesn't increase the
index any longer. It means it can write only first starting block index
so user couldn't write all idle pages in the zram so lose memory saving
chance.
This patch fixes those issues.
Link: https://lkml.kernel.org/r/20210312173949.2197662-2-minchan@xxxxxxxxxx
Fixes: 0d8359620d9b("zram: support page writeback")
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Reported-by: Amos Bianchi <amosbianchi@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: John Dias <joaodias@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -639,8 +639,8 @@ static ssize_t writeback_store(struct de
if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1))
return -EINVAL;
- ret = kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index);
- if (ret || index >= nr_pages)
+ if (kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index) ||
+ index >= nr_pages)
return -EINVAL;
nr_pages = 1;
@@ -664,7 +664,7 @@ static ssize_t writeback_store(struct de
goto release_init_lock;
}
- while (nr_pages--) {
+ for (; nr_pages != 0; index++, nr_pages--) {
struct bio_vec bvec;
bvec.bv_page = page;
Patches currently in stable-queue which might be from minchan@xxxxxxxxxx are
queue-5.11/zram-fix-return-value-on-writeback_store.patch
queue-5.11/mm-madvise-replace-ptrace-attach-requirement-for-process_madvise.patch
queue-5.11/zram-fix-broken-page-writeback.patch
queue-5.11/mm-userfaultfd-fix-memory-corruption-due-to-writeprotect.patch
