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 AB59CC4332F for ; Wed, 3 Nov 2021 18:20:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 867F36113B for ; Wed, 3 Nov 2021 18:20:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231359AbhKCSXD (ORCPT ); Wed, 3 Nov 2021 14:23:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:38244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230036AbhKCSW6 (ORCPT ); Wed, 3 Nov 2021 14:22:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DCF3F61058; Wed, 3 Nov 2021 18:20:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635963621; bh=FFi00w/SCD/3fQFpsM7+rPKbDql1iCHDgUj+gyZBz6A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ryP3DtXtXowf0J0FOPp8+cOTD4gihzfI3gzomyvNG4Ji0RnlY/rFbQJXodadnWiiD bZgNFCx0J8jlsUqsRZHr7tr4YbM2TQMoCVmGWg4RivKM2faAiQqRRDaP2kWewUzji/ zMsY/CVq5GlaOenCZsas8kUB2vOUqObHUcxXtMfDcfqqDaS/Yes/GKVeRDiAEagzUe Ghg/spxriWY6lSMgjaUAiIyGmdTL//Gmqy8xnJuGZTtH2qJ2q+LowWfZhij3VlsMVa LmNINM7rmPktnhby1zYGvMquIODdyoNa5NPsSxnQdHe528fW1nzKFMHD7tUObqjogD ZtTNkLFGBg5Hg== From: Gao Xiang To: linux-erofs@lists.ozlabs.org, Chao Yu Cc: LKML , Gao Xiang , stable@vger.kernel.org Subject: [PATCH v2] erofs: fix unsafe pagevec reuse of hooked pclusters Date: Thu, 4 Nov 2021 02:20:06 +0800 Message-Id: <20211103182006.4040-1-xiang@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20211103174953.3209-1-xiang@kernel.org> References: <20211103174953.3209-1-xiang@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support") Cc: # 4.19+ Signed-off-by: Gao Xiang --- changes since v1: - fix typos in commit message. 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 11c7a1aaebad..eb51df4a9f77 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -373,8 +373,8 @@ static 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; @@ -384,9 +384,9 @@ 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; } @@ -729,7 +729,8 @@ 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 short-lived page for pagevec */ if (err == -EAGAIN) { struct page *const newpage = @@ -737,7 +738,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE); 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 dfd7fe0503bb..b05464f4a808 100644 --- a/fs/erofs/zpvec.h +++ b/fs/erofs/zpvec.h @@ -106,11 +106,18 @@ 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); -- 2.20.1 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 AA63AC433F5 for ; Wed, 3 Nov 2021 18:20:29 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 029E761053 for ; Wed, 3 Nov 2021 18:20:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 029E761053 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Hkw6z4Wm5z2yHD for ; Thu, 4 Nov 2021 05:20:27 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=ryP3DtXt; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=xiang@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=ryP3DtXt; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Hkw6v5yc6z2xBf for ; Thu, 4 Nov 2021 05:20:23 +1100 (AEDT) Received: by mail.kernel.org (Postfix) with ESMTPSA id DCF3F61058; Wed, 3 Nov 2021 18:20:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635963621; bh=FFi00w/SCD/3fQFpsM7+rPKbDql1iCHDgUj+gyZBz6A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ryP3DtXtXowf0J0FOPp8+cOTD4gihzfI3gzomyvNG4Ji0RnlY/rFbQJXodadnWiiD bZgNFCx0J8jlsUqsRZHr7tr4YbM2TQMoCVmGWg4RivKM2faAiQqRRDaP2kWewUzji/ zMsY/CVq5GlaOenCZsas8kUB2vOUqObHUcxXtMfDcfqqDaS/Yes/GKVeRDiAEagzUe Ghg/spxriWY6lSMgjaUAiIyGmdTL//Gmqy8xnJuGZTtH2qJ2q+LowWfZhij3VlsMVa LmNINM7rmPktnhby1zYGvMquIODdyoNa5NPsSxnQdHe528fW1nzKFMHD7tUObqjogD ZtTNkLFGBg5Hg== From: Gao Xiang To: linux-erofs@lists.ozlabs.org, Chao Yu Subject: [PATCH v2] erofs: fix unsafe pagevec reuse of hooked pclusters Date: Thu, 4 Nov 2021 02:20:06 +0800 Message-Id: <20211103182006.4040-1-xiang@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20211103174953.3209-1-xiang@kernel.org> References: <20211103174953.3209-1-xiang@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: LKML , stable@vger.kernel.org Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" 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 Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support") Cc: # 4.19+ Signed-off-by: Gao Xiang --- changes since v1: - fix typos in commit message. 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 11c7a1aaebad..eb51df4a9f77 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -373,8 +373,8 @@ static 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; @@ -384,9 +384,9 @@ 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; } @@ -729,7 +729,8 @@ 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 short-lived page for pagevec */ if (err == -EAGAIN) { struct page *const newpage = @@ -737,7 +738,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE); 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 dfd7fe0503bb..b05464f4a808 100644 --- a/fs/erofs/zpvec.h +++ b/fs/erofs/zpvec.h @@ -106,11 +106,18 @@ 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); -- 2.20.1