The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 4b5d1e47b69426c0f7491d97d73ad0152d02d437 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023081217-gender-font-a356@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 4b5d1e47b694 ("zsmalloc: fix races between modifications of fullness and isolated") c0547d0b6a4b ("zsmalloc: consolidate zs_pool's migrate_lock and size_class's locks") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 4b5d1e47b69426c0f7491d97d73ad0152d02d437 Mon Sep 17 00:00:00 2001 From: Andrew Yang <andrew.yang@xxxxxxxxxxxx> Date: Fri, 21 Jul 2023 14:37:01 +0800 Subject: [PATCH] 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@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> 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 = {
