+ mm-swap-ratelimit-bad-swap-entry-reports.patch added to mm-unstable branch

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

The patch titled
     Subject: mm, swap: ratelimit bad swap entry reports
has been added to the -mm mm-unstable branch.  Its filename is
     mm-swap-ratelimit-bad-swap-entry-reports.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-ratelimit-bad-swap-entry-reports.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: Breno Leitao <leitao@debian.org>
Subject: mm, swap: ratelimit bad swap entry reports
Date: Tue, 18 Aug 2026 02:03:40 -0700

A corrupt page table hands the same bogus entry to get_swap_device() on
every access to the mapping, and every rejection is logged.  One machine
logged 6185620 copies of the same line in a few hours.

swap_dup_entry_direct() prints the same message from the fork path, once
per call: the WARN_ON_ONCE() guarding it warns once, the pr_err() inside
does not.

Rate limit all three prints.

Link: https://lore.kernel.org/20260818-swap_part_one-v1-1-a4fc58119fc0@debian.org
Fixes: 23b230ba8ac3 ("mm/swap: print bad swap offset entry in get_swap_device")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Kairui Song <kasong@tencent.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swapfile.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/mm/swapfile.c~mm-swap-ratelimit-bad-swap-entry-reports
+++ a/mm/swapfile.c
@@ -1899,11 +1899,11 @@ struct swap_info_struct *get_swap_device
 
 	return si;
 bad_nofile:
-	pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val);
+	pr_err_ratelimited("%s: %s%08lx\n", __func__, Bad_file, entry.val);
 out:
 	return NULL;
 put_out:
-	pr_err("%s: %s%08lx\n", __func__, Bad_offset, entry.val);
+	pr_err_ratelimited("%s: %s%08lx\n", __func__, Bad_offset, entry.val);
 	percpu_ref_put(&si->users);
 	return NULL;
 }
@@ -3883,7 +3883,7 @@ int swap_dup_entry_direct(swp_entry_t en
 
 	si = swap_entry_to_info(entry);
 	if (WARN_ON_ONCE(!si)) {
-		pr_err("%s%08lx\n", Bad_file, entry.val);
+		pr_err_ratelimited("%s%08lx\n", Bad_file, entry.val);
 		return -EINVAL;
 	}
 
_

Patches currently in -mm which might be from leitao@debian.org are

mm-kmemleak-report-rcu-tasks-quiescent-states-during-the-scan.patch
mm-kmemleak-report-leaks-only-after-n-consecutive-unreferenced-scans.patch
mm-kmemleak-factor-leak-confirmation-into-a-helper.patch
selftests-mm-test-kmemleaks-n-consecutive-scan-leak-confirmation.patch
mm-kmemleak-default-min_unref_scans-to-2-for-verbose-auto-scan.patch
documentation-kmemleak-document-the-conditional-min_unref_scans-default.patch
selftests-mm-kmemleak-drop-stale-min_unref_scans-default-from-comments.patch
mm-swap-ratelimit-bad-swap-entry-reports.patch