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authorAndrew Yang <andrew.yang@mediatek.com>2023-07-21 14:37:01 +0800
committerAndrew Morton <akpm@linux-foundation.org>2023-08-04 13:03:40 -0700
commit4b5d1e47b69426c0f7491d97d73ad0152d02d437 (patch)
tree0390b7e00167153964fac16bf16d713894ee5214 /mm
parent5d0c230f1de8c7515b6567d9afba1f196fb4e2f4 (diff)
zsmalloc: fix races between modifications of fullness and isolated
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@mediatek.com: move comment] Link: https://lkml.kernel.org/r/20230727062910.6337-1-andrew.yang@mediatek.com Link: https://lkml.kernel.org/r/20230721063705.11455-1-andrew.yang@mediatek.com Fixes: c4549b871102 ("zsmalloc: remove zspage isolation for migration") Signed-off-by: Andrew Yang <andrew.yang@mediatek.com> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/zsmalloc.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 3f057970504e..32916d28d9d9 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1798,6 +1798,7 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
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 *page, isolate_mode_t mode)
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 *newpage, struct page *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 *newpage, struct page *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 = {