+ mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2-fix.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2-fix
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-fix.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-fix.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: Andrew Morton <akpm@linux-foundation.org>
Subject: mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2-fix
Date: Fri Apr 12 04:18:11 PM PDT 2024

reflow block comment

Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory-failure.c |   18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2-fix
+++ a/mm/memory-failure.c
@@ -155,14 +155,16 @@ static int __page_handle_poison(struct p
 	int ret;
 
 	/*
-	 * zone_pcp_disable() can't be used here. It will hold pcp_batch_high_lock and
-	 * 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.
+	 * zone_pcp_disable() can't be used here. It will
+	 * hold pcp_batch_high_lock and 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 akpm@linux-foundation.org are

mm-memory-failure-fix-deadlock-when-hugetlb_optimize_vmemmap-is-enabled-v2-fix.patch
selftests-harness-remove-use-of-line_max-fix.patch
mm-sparc-change-pxd_huge-behavior-to-exclude-swap-entries-fix.patch
mm-hold-ptl-from-the-first-pte-while-reclaiming-a-large-folio-fix.patch
sh-remove-use-of-pg_arch_1-on-individual-pages-fix.patch
mm-gup-drop-folio_fast_pin_allowed-in-hugepd-processing-fix.patch
mm-allow-anon-exclusive-check-over-hugetlb-tail-pages-fix.patch
arm-mm-drop-vm_fault_badmap-vm_fault_badaccess-checkpatch-fixes.patch
__mod_memcg_lruvec_state-enhance-diagnostics.patch
__mod_memcg_lruvec_state-enhance-diagnostics-fix.patch