From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F3F7C433F5 for ; Tue, 16 Nov 2021 01:14:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4FB5860EFE for ; Tue, 16 Nov 2021 01:14:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245227AbhKPBRF (ORCPT ); Mon, 15 Nov 2021 20:17:05 -0500 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:42434 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377955AbhKPBNi (ORCPT ); Mon, 15 Nov 2021 20:13:38 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=hsiangkao@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UwmImHY_1637025037; Received: from e18g09479.et15sqa.tbsite.net(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0UwmImHY_1637025037) by smtp.aliyun-inc.com(127.0.0.1); Tue, 16 Nov 2021 09:10:40 +0800 From: Gao Xiang To: Greg Kroah-Hartman , stable@vger.kernel.org Cc: linux-erofs@lists.ozlabs.org, Gao Xiang , Chao Yu Subject: [PATCH 5.4.y 2/2] erofs: fix unsafe pagevec reuse of hooked pclusters Date: Tue, 16 Nov 2021 09:10:35 +0800 Message-Id: <20211116011035.124503-2-hsiangkao@linux.alibaba.com> X-Mailer: git-send-email 2.24.4 In-Reply-To: <20211116011035.124503-1-hsiangkao@linux.alibaba.com> References: <163698346111096@kroah.com> <20211116011035.124503-1-hsiangkao@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 86432a6dca9bed79111990851df5756d3eb5f57c upstream. There are pclusters in runtime marked with Z_EROFS_PCLUSTER_TAIL before actual I/O submission. Thus, the decompression chain can be extended if the following pcluster chain hooks such tail pcluster. As the related comment mentioned, if some page is made of a hooked pcluster and another followed pcluster, it can be reused for in-place I/O (since I/O should be submitted anyway): _______________________________________________________________ | tail (partial) page | head (partial) page | |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________| However, it's by no means safe to reuse as pagevec since if such PRIMARY_HOOKED pclusters finally move into bypass chain without I/O submission. It's somewhat hard to reproduce with LZ4 and I just found it (general protection fault) by ro_fsstressing a LZMA image for long time. I'm going to actively clean up related code together with multi-page folio adaption in the next few months. Let's address it directly for easier backporting for now. Call trace for reference: z_erofs_decompress_pcluster+0x10a/0x8a0 [erofs] z_erofs_decompress_queue.isra.36+0x3c/0x60 [erofs] z_erofs_runqueue+0x5f3/0x840 [erofs] z_erofs_readahead+0x1e8/0x320 [erofs] read_pages+0x91/0x270 page_cache_ra_unbounded+0x18b/0x240 filemap_get_pages+0x10a/0x5f0 filemap_read+0xa9/0x330 new_sync_read+0x11b/0x1a0 vfs_read+0xf1/0x190 Link: https://lore.kernel.org/r/20211103182006.4040-1-xiang@kernel.org Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support") Cc: # 4.19+ Reviewed-by: Chao Yu Signed-off-by: Gao Xiang --- fs/erofs/zdata.c | 13 +++++++------ fs/erofs/zpvec.h | 13 ++++++++++--- 2 files changed, 17 insertions(+), 9 deletions(-) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index f784feaeb819..fdd18c250811 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -288,8 +288,8 @@ static inline bool z_erofs_try_inplace_io(struct z_erofs_collector *clt, /* callers must be with collection lock held */ static int z_erofs_attach_page(struct z_erofs_collector *clt, - struct page *page, - enum z_erofs_page_type type) + struct page *page, enum z_erofs_page_type type, + bool pvec_safereuse) { int ret; @@ -299,9 +299,9 @@ static int z_erofs_attach_page(struct z_erofs_collector *clt, z_erofs_try_inplace_io(clt, page)) return 0; - ret = z_erofs_pagevec_enqueue(&clt->vector, page, type); + ret = z_erofs_pagevec_enqueue(&clt->vector, page, type, + pvec_safereuse); clt->cl->vcnt += (unsigned int)ret; - return ret ? 0 : -EAGAIN; } @@ -652,14 +652,15 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED); retry: - err = z_erofs_attach_page(clt, page, page_type); + err = z_erofs_attach_page(clt, page, page_type, + clt->mode >= COLLECT_PRIMARY_FOLLOWED); /* should allocate an additional staging page for pagevec */ if (err == -EAGAIN) { struct page *const newpage = __stagingpage_alloc(pagepool, GFP_NOFS); err = z_erofs_attach_page(clt, newpage, - Z_EROFS_PAGE_TYPE_EXCLUSIVE); + Z_EROFS_PAGE_TYPE_EXCLUSIVE, true); if (!err) goto retry; } diff --git a/fs/erofs/zpvec.h b/fs/erofs/zpvec.h index a38c52610367..6a20b2c3a24c 100644 --- a/fs/erofs/zpvec.h +++ b/fs/erofs/zpvec.h @@ -107,11 +107,18 @@ static inline void z_erofs_pagevec_ctor_init(struct z_erofs_pagevec_ctor *ctor, static inline bool z_erofs_pagevec_enqueue(struct z_erofs_pagevec_ctor *ctor, struct page *page, - enum z_erofs_page_type type) + enum z_erofs_page_type type, + bool pvec_safereuse) { - if (!ctor->next && type) - if (ctor->index + 1 == ctor->nr) + if (!ctor->next) { + /* some pages cannot be reused as pvec safely without I/O */ + if (type == Z_EROFS_PAGE_TYPE_EXCLUSIVE && !pvec_safereuse) + type = Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED; + + if (type != Z_EROFS_PAGE_TYPE_EXCLUSIVE && + ctor->index + 1 == ctor->nr) return false; + } if (ctor->index >= ctor->nr) z_erofs_pagevec_ctor_pagedown(ctor, false); -- 2.24.4