diff options
| author | Andrew Yang | 2023-07-21 14:37:01 +0800 |
|---|---|---|
| committer | Andrew Morton | 2023-08-04 13:03:40 -0700 |
| commit | 4b5d1e47b69426c0f7491d97d73ad0152d02d437 (patch) | |
| tree | 0390b7e00167153964fac16bf16d713894ee5214 | |
| parent | 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4 (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>
| -rw-r--r-- | mm/zsmalloc.c | 14 |
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 = { |