From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E32B52D2495; Wed, 7 Oct 2026 00:50:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791334202; cv=none; b=rkzd2EsU8WyCYXiJX0EMlwO8GXzlVsyz7WplDQglJSrexZr38jJ9wuXPGh5pkgHtyVOxupJct2Zn7ZAXppMRCbjtWkNoPXlycLKVjhVbCFkytE7Kq6nQiR3LzhfS+V2rmgNeANjClHi5NicLwIm3p568bYs46SUt/VxkmxM53EQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791334202; c=relaxed/simple; bh=uA2pwhcKYLqQCbhUmtS6Eu+pt1zUBrrnVR7hnoxQrwI=; h=Date:To:From:Subject:Message-Id; b=i+5aaFgFUAn1QAfHAtMePabsKPgqpXGhnTK8E4DMuDlfojcUhcs6cMqpThyThmQ+ACjXnXPVieOyR+EU/tdm3hQ5rSyNg4YgjRJfhB27m7PkC1OyX9z45FGjpqGQp6PuDKcsXkJ4/0HDa1B2Mf5BcPXpZ3AE0zDFV3ffWyhx0OI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=FlqKM9WT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="FlqKM9WT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7B921F0089E; Wed, 7 Oct 2026 00:50:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791334200; bh=2h04ca7eJosoZhTP/Zi8aey9EnF0bbunoshTK1A994Q=; h=Date:To:From:Subject; b=FlqKM9WTXU2yOD7IMQDbplFc5Q00ccIoJ0ktTs3szwIkjmeT1dLtkRGFiieVOPmY1 xNQfz9+U8LGdNeKMrST/x/s2r5dtf17i61Ncl0UZj4ZS6ovtI0K0aSxehltw1R/6Ro Tf9sNsUwVrqSsliPkiCAgm4cJITHo71x4SIJ+6sQ= Date: Tue, 06 Oct 2026 17:50:00 -0700 To: mm-commits@vger.kernel.org,zokeefe@google.com,stable@vger.kernel.org,ryan.roberts@arm.com,ljs@kernel.org,lance.yang@linux.dev,dev.jain@arm.com,david@kernel.org,baohua@kernel.org,yanglincheng@kylinos.cn,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-khugepaged-fix-folio-is-used-after-folio_put-unlock.patch removed from -mm tree Message-Id: <20261007005000.B7B921F0089E@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: khugepaged: fix folio is used after folio_put/unlock() has been removed from the -mm tree. Its filename was mm-khugepaged-fix-folio-is-used-after-folio_put-unlock.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Vernon Yang Subject: mm: khugepaged: fix folio is used after folio_put/unlock() Date: Wed, 9 Sep 2026 10:58:03 +0800 On the rollback path, folio_put() has already dropped the last reference of new_folio. On the success path, new_folio is already unlocked and can be freed concurrently. The trace_mm_khugepaged_collapse_file() is left with a dangling folio pointer. So using the folio_pfn() before dropping the reference, closing use-after-free window. Link: https://lore.kernel.org/20260909025804.3233645-4-vernon2gm@gmail.com Fixes: 4c9473e87e75 ("mm/khugepaged: add tracepoint to collapse_file()") Signed-off-by: Vernon Yang Signed-off-by: Andrew Morton Acked-by: David Hildenbrand (Arm) Acked-by: Lorenzo Stoakes (ARM) Cc: Barry Song Cc: Dev Jain Cc: Lance Yang Cc: Ryan Roberts Cc: Zach O'Keefe Cc: --- include/trace/events/huge_memory.h | 6 +++--- mm/khugepaged.c | 4 +++- 2 files changed, 6 insertions(+), 4 deletions(-) --- a/include/trace/events/huge_memory.h~mm-khugepaged-fix-folio-is-used-after-folio_put-unlock +++ a/include/trace/events/huge_memory.h @@ -211,10 +211,10 @@ TRACE_EVENT(mm_khugepaged_scan_file, ); TRACE_EVENT(mm_khugepaged_collapse_file, - TP_PROTO(struct mm_struct *mm, struct folio *new_folio, pgoff_t index, + TP_PROTO(struct mm_struct *mm, unsigned long new_pfn, pgoff_t index, unsigned long addr, bool is_shmem, struct file *file, int nr, int result), - TP_ARGS(mm, new_folio, index, addr, is_shmem, file, nr, result), + TP_ARGS(mm, new_pfn, index, addr, is_shmem, file, nr, result), TP_STRUCT__entry( __field(struct mm_struct *, mm) __field(unsigned long, hpfn) @@ -228,7 +228,7 @@ TRACE_EVENT(mm_khugepaged_collapse_file, TP_fast_assign( __entry->mm = mm; - __entry->hpfn = new_folio ? folio_pfn(new_folio) : -1; + __entry->hpfn = new_pfn; __entry->index = index; __entry->addr = addr; __entry->is_shmem = is_shmem; --- a/mm/khugepaged.c~mm-khugepaged-fix-folio-is-used-after-folio_put-unlock +++ a/mm/khugepaged.c @@ -2253,6 +2253,7 @@ static enum scan_result collapse_file(st struct address_space *mapping = file->f_mapping; struct page *dst; struct folio *folio, *tmp, *new_folio; + unsigned long new_pfn = -1; pgoff_t index = 0, end = start + HPAGE_PMD_NR; LIST_HEAD(pagelist); XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); @@ -2272,6 +2273,7 @@ static enum scan_result collapse_file(st result = alloc_charge_folio(&new_folio, mm, cc, HPAGE_PMD_ORDER); if (result != SCAN_SUCCEED) goto out; + new_pfn = folio_pfn(new_folio); mapping_set_update(&xas, mapping); @@ -2675,7 +2677,7 @@ rollback: folio_put(new_folio); out: VM_BUG_ON(!list_empty(&pagelist)); - trace_mm_khugepaged_collapse_file(mm, new_folio, index, addr, is_shmem, file, HPAGE_PMD_NR, result); + trace_mm_khugepaged_collapse_file(mm, new_pfn, index, addr, is_shmem, file, HPAGE_PMD_NR, result); return result; } _ Patches currently in -mm which might be from yanglincheng@kylinos.cn are