The quilt patch titled
Subject: zsmalloc: fix races between modifications of fullness and isolated
has been removed from the -mm tree. Its filename was
zsmalloc-fix-races-between-modifications-of-fullness-and-isolated.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Andrew Yang <andrew.yang@xxxxxxxxxxxx>
Subject: zsmalloc: fix races between modifications of fullness and isolated
Date: Fri, 21 Jul 2023 14:37:01 +0800
We encountered many kernel exceptions of VM_BUG_ON(zspage->isolated ==
0) in dec_zspage_isolation() and BUG_ON(!pages[1]) in zs_unmap_object()
lately. This issue only occurs when migration and reclamation occur at
the same time.
With our memory stress test, we can reproduce this issue several times
a day. We have no idea why no one else encountered this issue. BTW,
we switched to the new kernel version with this defect a few months
ago.
Since fullness and isolated share the same unsigned int, modifications of
them should be protected by the same lock.
[andrew.yang@xxxxxxxxxxxx: move comment]
Link: https://lkml.kernel.org/r/20230727062910.6337-1-andrew.yang@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20230721063705.11455-1-andrew.yang@xxxxxxxxxxxx
Fixes: c4549b871102 ("zsmalloc: remove zspage isolation for migration")
Signed-off-by: Andrew Yang <andrew.yang@xxxxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--- a/mm/zsmalloc.c~zsmalloc-fix-races-between-modifications-of-fullness-and-isolated
+++ a/mm/zsmalloc.c
@@ -1798,6 +1798,7 @@ static void replace_sub_page(struct size
static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
{
+ struct zs_pool *pool;
struct zspage *zspage;
/*
@@ -1807,9 +1808,10 @@ static bool zs_page_isolate(struct page
VM_BUG_ON_PAGE(PageIsolated(page), page);
zspage = get_zspage(page);
- migrate_write_lock(zspage);
+ pool = zspage->pool;
+ spin_lock(&pool->lock);
inc_zspage_isolation(zspage);
- migrate_write_unlock(zspage);
+ spin_unlock(&pool->lock);
return true;
}
@@ -1875,12 +1877,12 @@ static int zs_page_migrate(struct page *
kunmap_atomic(s_addr);
replace_sub_page(class, zspage, newpage, page);
+ dec_zspage_isolation(zspage);
/*
* Since we complete the data copy and set up new zspage structure,
* it's okay to release the pool's lock.
*/
spin_unlock(&pool->lock);
- dec_zspage_isolation(zspage);
migrate_write_unlock(zspage);
get_page(newpage);
@@ -1897,14 +1899,16 @@ static int zs_page_migrate(struct page *
static void zs_page_putback(struct page *page)
{
+ struct zs_pool *pool;
struct zspage *zspage;
VM_BUG_ON_PAGE(!PageIsolated(page), page);
zspage = get_zspage(page);
- migrate_write_lock(zspage);
+ pool = zspage->pool;
+ spin_lock(&pool->lock);
dec_zspage_isolation(zspage);
- migrate_write_unlock(zspage);
+ spin_unlock(&pool->lock);
}
static const struct movable_operations zsmalloc_mops = {
_
Patches currently in -mm which might be from andrew.yang@xxxxxxxxxxxx are
fs-drop_caches-draining-pages-before-dropping-caches.patch
