The patch titled
Subject: mm: check all swaps belong to same swap_cgroup in swap_pte_batch()
has been added to the -mm mm-unstable branch. Its filename is
mm-attempt-to-batch-free-swap-entries-for-zap_pte_range-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-attempt-to-batch-free-swap-entries-for-zap_pte_range-fix.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: Barry Song <v-songbaohua@xxxxxxxx>
Subject: mm: check all swaps belong to same swap_cgroup in swap_pte_batch()
Date: Fri, 16 Aug 2024 09:36:23 +1200
Right now, it is possible two folios are contiguous in swap slots but they
don't belong to one memcg. In this case, even we return a large nr, we
can't really batch free all slots.
Link: https://lkml.kernel.org/r/20240815215308.55233-1-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Reported-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Reported-by: Chris Li <chrisl@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/internal.h | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/internal.h~mm-attempt-to-batch-free-swap-entries-for-zap_pte_range-fix
+++ a/mm/internal.h
@@ -15,6 +15,7 @@
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/swapops.h>
+#include <linux/swap_cgroup.h>
#include <linux/tracepoint-defs.h>
/* Internal core VMA manipulation functions. */
@@ -275,18 +276,22 @@ static inline int swap_pte_batch(pte_t *
{
pte_t expected_pte = pte_next_swp_offset(pte);
const pte_t *end_ptep = start_ptep + max_nr;
+ swp_entry_t entry = pte_to_swp_entry(pte);
pte_t *ptep = start_ptep + 1;
+ unsigned short cgroup_id;
VM_WARN_ON(max_nr < 1);
VM_WARN_ON(!is_swap_pte(pte));
- VM_WARN_ON(non_swap_entry(pte_to_swp_entry(pte)));
+ VM_WARN_ON(non_swap_entry(entry));
+ cgroup_id = lookup_swap_cgroup_id(entry);
while (ptep < end_ptep) {
pte = ptep_get(ptep);
if (!pte_same(pte, expected_pte))
break;
-
+ if (lookup_swap_cgroup_id(pte_to_swp_entry(pte)) != cgroup_id)
+ break;
expected_pte = pte_next_swp_offset(expected_pte);
ptep++;
}
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
mm-extend-usage-parameter-so-that-cluster_swap_free_nr-can-be-reused.patch
mm-swap-add-nr-argument-in-swapcache_prepare-and-swapcache_clear-to-support-large-folios.patch
mm-swap-add-nr-argument-in-swapcache_prepare-and-swapcache_clear-to-support-large-folios-fix.patch
vpda-try-to-fix-the-potential-crash-due-to-misusing-__gfp_nofail.patch
mm-document-__gfp_nofail-must-be-blockable.patch
mm-bug_on-to-avoid-null-deference-while-__gfp_nofail-fails.patch
mm-prohibit-null-deference-exposed-for-unsupported-non-blockable-__gfp_nofail.patch
mm-add-nr-argument-in-mem_cgroup_swapin_uncharge_swap-helper-to-support-large-folios.patch
mm-rename-instances-of-swap_info_struct-to-meaningful-si.patch
mm-attempt-to-batch-free-swap-entries-for-zap_pte_range.patch
mm-attempt-to-batch-free-swap-entries-for-zap_pte_range-fix.patch
