The patch titled
Subject: mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled
Date: Fri, 12 Apr 2024 10:57:54 +0800
extend comment per Oscar
Link: https://lkml.kernel.org/r/20240412025754.1897615-1-linmiaohe@xxxxxxxxxx
Fixes: a6b40850c442 ("mm: hugetlb: replace hugetlb_free_vmemmap_enabled with a static_key")
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Acked-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/memory-failure.c~mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2
+++ a/mm/memory-failure.c
@@ -159,6 +159,10 @@ static int __page_handle_poison(struct p
* dissolve_free_huge_page() might hold cpu_hotplug_lock via static_key_slow_dec()
* when hugetlb vmemmap optimization is enabled. This will break current lock
* dependency chain and leads to deadlock.
+ * Disabling pcp before dissolving the page was a deterministic approach because
+ * we made sure that those pages cannot end up in any PCP list. Draining PCP lists
+ * expels those pages to the buddy system, but nothing guarantees that those pages
+ * do not get back to a PCP queue if we need to refill those.
*/
ret = dissolve_free_huge_page(page);
if (!ret) {
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled.patch
mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2.patch
fork-defer-linking-file-vma-until-vma-is-fully-initialized.patch
