From nobody Mon Feb 9 10:38:41 2026 Received: from SHSQR01.spreadtrum.com (unknown [222.66.158.135]) (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 6D95C433D4 for ; Thu, 14 Mar 2024 08:39:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=222.66.158.135 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710405602; cv=none; b=BFSAvzK+jJdLavruDPLup6jeKSdULnC0Ao/xPtTWW085gxvzy3T7OZ272/MpKW7bxKR3/7u81NcUfcem+UHRQdZydpnMj0yqz9jvT8qebvsoN7O02Iyt11kMdKW+EGPp0BhHAot3MIfR4kxdAN+oSykdCj7klh2zxSgUkbtvSEY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710405602; c=relaxed/simple; bh=hXBkc2lnJyVmaqMJ7BzFl8A8231c++GoATT9FbJj3YY=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; b=T09oZq1t/cInw5ulavJEbgQ/Ie4uIJWst/pGg4KM3p4dA8TBzDKfWx2huRupQlctJFU/RwThGW7AmtFj0v5d7gjw9oMFhBPaj0377oOaIQ5iiYEm6Zau7oNUmdOc8PkUAhaShWIGJoAfHPCzKaNXfdBhakfGAgKcQzfMWaOj+8U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=unisoc.com; spf=pass smtp.mailfrom=unisoc.com; arc=none smtp.client-ip=222.66.158.135 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=unisoc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=unisoc.com Received: from dlp.unisoc.com ([10.29.3.86]) by SHSQR01.spreadtrum.com with ESMTP id 42E8dQ2t042813; Thu, 14 Mar 2024 16:39:26 +0800 (+08) (envelope-from zhaoyang.huang@unisoc.com) Received: from SHDLP.spreadtrum.com (bjmbx01.spreadtrum.com [10.0.64.7]) by dlp.unisoc.com (SkyGuard) with ESMTPS id 4TwLPF1QZbz2L2Bvr; Thu, 14 Mar 2024 16:38:09 +0800 (CST) Received: from bj03382pcu01.spreadtrum.com (10.0.73.40) by BJMBX01.spreadtrum.com (10.0.64.7) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Thu, 14 Mar 2024 16:39:24 +0800 From: "zhaoyang.huang" To: Andrew Morton , , , Zhaoyang Huang , Subject: [PATCH] mm: fix a race scenario in folio_isolate_lru Date: Thu, 14 Mar 2024 16:39:21 +0800 Message-ID: <20240314083921.1146937-1-zhaoyang.huang@unisoc.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SHCAS01.spreadtrum.com (10.0.1.201) To BJMBX01.spreadtrum.com (10.0.64.7) X-MAIL: SHSQR01.spreadtrum.com 42E8dQ2t042813 Content-Type: text/plain; charset="utf-8" From: Zhaoyang Huang Panic[1] reported which is caused by lruvec->list break. Fix the race between folio_isolate_lru and release_pages. race condition: release_pages could meet a non-refered folio which escaped from being deleted from LRU but add to another list_head #0 folio_isolate_lru #1 release_pages if (folio_test_clear_lru()) if (folio_put_testzero()) if (!folio_test_lru()) folio_get(folio) list_add(&folio->lru,) list_del(&folio->lru,) fix action 1: have folio_get prior to folio_test_clear_lru is not enough as there could be concurrent folio_put(filemap_remove_folios) to make release_pages pass refcnt check and failed in delete from LRU #0 folio_isolate_lru #1 release_pages folio_get(folio) if (folio_test_clear_lru()) if (folio_put_testzero()) if (!folio_test_lru()) list_add(&folio->lru,) list_del(&folio->lru,) fix action 2: folio_test_clear_lru should be considered as part of critical section of lruvec which require be within lruvec->lock. #0 folio_isolate_lru #1 release_pages spin_lock(lruvec->lock) folio_get(folio) if (folio_test_clear_lru()) list_del(&folio->lru,) spin_unlock(lruvec->lock) spin_lock(lruvec->lock) if (folio_put_testzero()) if (!folio_test_lru()) list_add(&folio->lru,) [1] [ 37.562326] pc : __list_del_entry_valid_or_report+0xec/0xf0 [ 37.562344] lr : __list_del_entry_valid_or_report+0xec/0xf0 [ 37.562351] sp : ffffffc085953990 [ 37.562355] x29: ffffffc0859539d0 x28: ffffffc082144000 x27: 00000000000= 0000f [ 37.562367] x26: 000000000000000d x25: 000000000000000d x24: 00000000fff= fffff [ 37.562377] x23: ffffffc085953a08 x22: ffffff8080389000 x21: ffffff80803= 89000 [ 37.562388] x20: fffffffe05c54180 x19: ffffffc085953b30 x18: ffffffc0859= 89098 [ 37.562399] x17: 20747562202c3838 x16: ffffffffffffffff x15: 00000000000= 00004 [ 37.562409] x14: ffffff8176980000 x13: 0000000000007fff x12: 00000000000= 00003 [ 37.562420] x11: 00000000ffff7fff x10: ffffffc0820f51c4 x9 : 53b71233d5d= 50e00 [ 37.562431] x8 : 53b71233d5d50e00 x7 : ffffffc081161ff0 x6 : 00000000000= 00000 [ 37.562441] x5 : 0000000000000001 x4 : 0000000000000001 x3 : 00000000000= 00000 [ 37.562451] x2 : ffffff817f2c4178 x1 : ffffff817f2b71c8 x0 : 00000000000= 0006d [ 37.562461] Call trace: [ 37.562465] __list_del_entry_valid_or_report+0xec/0xf0 [ 37.562472] release_pages+0x410/0x4c0 [ 37.562482] __folio_batch_release+0x34/0x4c [ 37.562490] truncate_inode_pages_range+0x368/0x63c [ 37.562497] truncate_inode_pages+0x14/0x24 [ 37.562504] blkdev_flush_mapping+0x60/0x120 [ 37.562513] blkdev_put+0x114/0x298 [ 37.562520] blkdev_release+0x28/0x40 [ 37.562526] __fput+0xf8/0x2a8 [ 37.562533] ____fput+0x10/0x20 [ 37.562539] task_work_run+0xc4/0xec [ 37.562546] do_exit+0x32c/0xa3c [ 37.562554] do_group_exit+0x98/0x9c [ 37.562561] __arm64_sys_exit_group+0x18/0x1c [ 37.562568] invoke_syscall+0x58/0x114 [ 37.562575] el0_svc_common+0xac/0xe0 [ 37.562582] do_el0_svc+0x1c/0x28 [ 37.562588] el0_svc+0x50/0xe4 [ 37.562593] el0t_64_sync_handler+0x68/0xbc [ 37.562599] el0t_64_sync+0x1a8/0x1ac Signed-off-by: Zhaoyang Huang --- mm/swap.c | 25 +++++++++++++++++-------- mm/vmscan.c | 25 +++++++++++++++++++------ 2 files changed, 36 insertions(+), 14 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index cd8f0150ba3a..287cf7379927 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -968,6 +968,7 @@ void release_pages(release_pages_arg arg, int nr) =20 for (i =3D 0; i < nr; i++) { struct folio *folio; + struct lruvec *prev_lruvec; =20 /* Turn any of the argument types into a folio */ folio =3D page_folio(encoded_page_ptr(encoded[i])); @@ -996,9 +997,24 @@ void release_pages(release_pages_arg arg, int nr) free_zone_device_page(&folio->page); continue; } + /* + * lruvec->lock need to be prior to folio_put_testzero to + * prevent race with folio_isolate_lru + */ + prev_lruvec =3D lruvec; + lruvec =3D folio_lruvec_relock_irqsave(folio, lruvec, + &flags); + + if (prev_lruvec !=3D lruvec) + lock_batch =3D 0; =20 - if (!folio_put_testzero(folio)) + if (!folio_put_testzero(folio)) { + if (lruvec) { + unlock_page_lruvec_irqrestore(lruvec, flags); + lruvec =3D NULL; + } continue; + } =20 if (folio_test_large(folio)) { if (lruvec) { @@ -1010,13 +1026,6 @@ void release_pages(release_pages_arg arg, int nr) } =20 if (folio_test_lru(folio)) { - struct lruvec *prev_lruvec =3D lruvec; - - lruvec =3D folio_lruvec_relock_irqsave(folio, lruvec, - &flags); - if (prev_lruvec !=3D lruvec) - lock_batch =3D 0; - lruvec_del_folio(lruvec, folio); __folio_clear_lru_flags(folio); } diff --git a/mm/vmscan.c b/mm/vmscan.c index 4255619a1a31..13a4a716c67a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1721,18 +1721,31 @@ static unsigned long isolate_lru_folios(unsigned lo= ng nr_to_scan, bool folio_isolate_lru(struct folio *folio) { bool ret =3D false; + struct lruvec *lruvec; =20 VM_BUG_ON_FOLIO(!folio_ref_count(folio), folio); =20 - if (folio_test_clear_lru(folio)) { - struct lruvec *lruvec; + /* + * The folio_get needs to be prior to clear lru for list integrity. + * Otherwise: + * #0 folio_isolate_lru #1 release_pages + * if (folio_test_clear_lru()) + * if (folio_put_testzero()) + * if (!folio_test_lru()) + * + * folio_get(folio) + * list_add(&folio->lru,) + * list_del(&folio->lru,) + */ + lruvec =3D folio_lruvec_lock_irq(folio); + folio_get(folio); =20 - folio_get(folio); - lruvec =3D folio_lruvec_lock_irq(folio); + if (folio_test_clear_lru(folio)) { lruvec_del_folio(lruvec, folio); - unlock_page_lruvec_irq(lruvec); ret =3D true; - } + } else + folio_put(folio); + unlock_page_lruvec_irq(lruvec); =20 return ret; } --=20 2.25.1