+ mm-page_alloc-fix-freeing-static-percpu-memory.patch added to mm-unstable branch

+ mm-page_alloc-fix-freeing-static-percpu-memory.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/page_alloc: fix freeing static percpu memory
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-fix-freeing-static-percpu-memory.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-fix-freeing-static-percpu-memory.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/page_alloc: fix freeing static percpu memory
Date: Fri, 16 Sep 2022 15:22:47 +0800

The size of struct per_cpu_zonestat can be 0 on !SMP && !NUMA.  In that
case, zone->per_cpu_zonestats will always equal to boot_zonestats.  But in
zone_pcp_reset(), zone->per_cpu_zonestats is freed via free_percpu()
directly without checking against boot_zonestats first.  boot_zonestats
will be released by free_percpu() unexpectedly.

Link: https://lkml.kernel.org/r/20220916072257.9639-7-linmiaohe@huawei.com
Fixes: 28f836b6777b ("mm/page_alloc: split per cpu page lists and zone stats")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-fix-freeing-static-percpu-memory
+++ a/mm/page_alloc.c
@@ -9505,9 +9505,11 @@ void zone_pcp_reset(struct zone *zone)
 			drain_zonestat(zone, pzstats);
 		}
 		free_percpu(zone->per_cpu_pageset);
-		free_percpu(zone->per_cpu_zonestats);
 		zone->per_cpu_pageset = &boot_pageset;
-		zone->per_cpu_zonestats = &boot_zonestats;
+		if (zone->per_cpu_zonestats != &boot_zonestats) {
+			free_percpu(zone->per_cpu_zonestats);
+			zone->per_cpu_zonestats = &boot_zonestats;
+		}
 	}
 }
 
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-hwpoison-use-clearpagehwpoison-in-memory_failure.patch
mm-hwpoison-use-__pagemovable-to-detect-non-lru-movable-pages.patch
mm-hwpoison-use-num_poisoned_pages_sub-to-decrease-num_poisoned_pages.patch
mm-hwpoison-avoid-unneeded-page_mapped_in_vma-overhead-in-collect_procs_anon.patch
mm-hwpoison-check-pagetable-explicitly-in-hwpoison_user_mappings.patch
mm-hwpoison-cleanup-some-obsolete-comments.patch
writeback-remove-unused-macro-dirty_full_scope.patch
mm-page_alloc-ensure-kswapd-doesnt-accidentally-go-to-sleep.patch
mm-page_alloc-make-zone_pcp_update-static.patch
mm-remove-obsolete-macro-nr_pcp_order_mask-and-nr_pcp_order_width.patch
mm-page_alloc-remove-obsolete-comment-in-zone_statistics.patch
mm-page_alloc-add-__init-annotations-to-init_mem_debugging_and_hardening.patch
mm-page_alloc-fix-freeing-static-percpu-memory.patch
mm-remove-obsolete-pgdat_is_empty.patch
mm-page_alloc-add-missing-is_migrate_isolate-check-in-set_page_guard.patch
mm-page_alloc-use-local-variable-zone_idx-directly.patch
mm-memory_hotplug-remove-obsolete-generic_free_nodedata.patch
mm-page_alloc-make-boot_nodestats-static.patch
mm-page_alloc-use-helper-macro-sz_1km.patch
mm-page_alloc-init-local-variable-buddy_pfn.patch
mm-page_alloc-use-costly_order-in-warn_on_once_gfp.patch
mm-page_alloc-remove-obsolete-gfpflags_normal_context.patch
mm-page_alloc-fix-obsolete-comment-in-deferred_pfn_valid.patch