From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793801954; b=I1NcYxPwf/ZBREX6r87YWQDitKJBysJK/J7LJezbxEVgAZKIy0tBt8hRWK5jLcylSzeK 4rYM32gwAy/qyFx559dAhi6ayhrYAgx8zXV9W3L3jSYc7stLnlKDtQ7gXRS8ZXjCqYdfn Wx7pu42+9fC6uWRb1PS97bfXhHCwd14+oMTZllk3sAIC8TSz+aU0FU00Ccatbz436i+xm h0CgbMnNsRwzejL5hUYZOhO7Glb+EMRj8EfEt8PHTi7RNvnF9xHzaj+BACmsxrzd4YjZu ZwE7q1yXR1bjZ8ZQbtgwWGq6zu28QHUGBbaoDmd9SIJbiaxGCIZMEoq9oj/KS1C+/0w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793801954; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=Bj/g7o71Zed+1Va5Vai+bkcv41XUcj0kv6daT+lrMpE=; b=Jd3tgrjwdJTvqlqElE+s/iiiduY0zE2SjVZf+EA7dbaTLocj7Vi4t2ATTgdGGIIJQqz6 ttt8h1EHDIggCROoXnCbw2uR77adyIptbPczX2KtYpJCHPICTYW7c4yvbPqWuV6jktdhR lt1bEzsg+0vtoVDsNdQV6h23X9+/eiBsZ2LpyC8CgmnxCyuRe1UUt2IvY3/xhsUEKBGNp MZePQ83buysCgOH07sIoTOBAHgcyKIKNBpjL0pdypyueAnESsYMggDwTYsJYrxxTemfIx KcxzPtR8r3HniPzZIBcPL7jFuFnBwdCMK7v+QVupnUh51+DmSMdr9mz8VW+SwhJmgVQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="yaJphJ/y"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 93E19606A31B for ; Wed, 4 Nov 2026 14:19:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=yaJphJ/y Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2ADE1F000C1; Wed, 4 Nov 2026 14:19:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793801954; bh=Bj/g7o71Zed+1Va5Vai+bkcv41XUcj0kv6daT+lrMpE=; h=Subject:To:Cc:From:Date; b=yaJphJ/yPR8jO93JMjkEmppnj5k1kdzj+dBIZpPh08Bw0QW+kAKIAgwHPdQyw8hhp jMyI2pd1GOVzpXs+X1rC2oCzzdCBkauSzhe/t45jsc6dyVG6RGRffSWUKRgRgquDHv SCAQSTw/HJI8iy3ButN9d6ikocvwxBeVTtK0hkCw= Subject: FAILED: patch "[PATCH] mm: khugepaged: fix folio is used after folio_put/unlock()" failed to apply to 6.6-stable tree To: yanglincheng@kylinos.cn,akpm@linux-foundation.org,baohua@kernel.org,david@kernel.org,dev.jain@arm.com,lance.yang@linux.dev,ljs@kernel.org,ryan.roberts@arm.com,stable@vger.kernel.org,zokeefe@google.com Cc: From: Date: Wed, 04 Nov 2026 15:19:13 +0100 Message-ID: <2026110413-cacti-bonded-6534@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 9010383e71e6ce75fcd3c8f87133c8ce6c0e6ab4 # git commit -s git send-email --to '' --in-reply-to '2026110413-cacti-bonded-6534@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 9010383e71e6ce75fcd3c8f87133c8ce6c0e6ab4 Mon Sep 17 00:00:00 2001 From: Vernon Yang Date: Wed, 9 Sep 2026 10:58:03 +0800 Subject: [PATCH] mm: khugepaged: fix folio is used after folio_put/unlock() 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: diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h index fa828967e1fb..5fb4d92cfd84 100644 --- a/include/trace/events/huge_memory.h +++ b/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; diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 730829947b4c..792166950bba 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2253,6 +2253,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, 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(struct mm_struct *mm, unsigned long addr, 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 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, 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; }