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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FC05C433DF for ; Mon, 19 Oct 2020 10:14:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2325722268 for ; Mon, 19 Oct 2020 10:14:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="usqFcIX/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725921AbgJSKOC (ORCPT ); Mon, 19 Oct 2020 06:14:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725892AbgJSKOC (ORCPT ); Mon, 19 Oct 2020 06:14:02 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8B2AC0613CE; Mon, 19 Oct 2020 03:14:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=4ZUsuMrR+ngWpncutSCoMS/lWOgKT6Cj9cHkeDMetR0=; b=usqFcIX/i+y71mXlgiCmt07zPf 3GhE+28+QPqGVJEeCsK6m/+gyJ2SoyTGn6vthGjNUeXDKMBvpztWgc6iZXcpYvzluOq5ZFdb1GpZF jeVyYJ78fusnRlk8MH7yyIeehMAolr8QLdll8bczFg7EW1AupGLl+Qv3r4H0/Qgmq/LOo7gUPJxpi h2ep0USqn2voW1yuaECtBbzehj6yAeWYqtbyC6Nkh0BP1NugiBOV/5buw1x97OU9Et3nvMoscX57L ZvS1/r8M5QLWM6cD4qEwb1tlDq0CmouxSIHCgn6hYxEzBC0qHRrUnPaZNodjwoGsv222RX5rh7epH wDakJl8g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kUSAt-0002S3-1F; Mon, 19 Oct 2020 10:13:55 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id ACA9A3035D4; Mon, 19 Oct 2020 12:13:53 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 93F622B07595D; Mon, 19 Oct 2020 12:13:53 +0200 (CEST) Date: Mon, 19 Oct 2020 12:13:53 +0200 From: Peter Zijlstra To: Minchan Kim Cc: Mikhail Gavrilov , Linux List Kernel Mailing , linux-block@vger.kernel.org, Mike Galbraith , ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, bigeasy@linutronix.de, Andrew Morton Subject: [PATCH] zram: Fix __zram_bvec_{read,write}() locking order Message-ID: <20201019101353.GJ2628@hirez.programming.kicks-ass.net> References: <20201016124009.GQ2611@hirez.programming.kicks-ass.net> <20201016153324.GA1976566@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201016153324.GA1976566@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Mikhail reported a lockdep spat detailing how __zram_bvec_read() and __zram_bvec_write() use zstrm->lock and zspage->lock in opposite order. Reported-by: Mikhail Gavrilov Signed-off-by: Peter Zijlstra (Intel) Tested-by: Mikhail Gavrilov --- drivers/block/zram/zram_drv.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 9100ac36670a..c1e2c2e1cde8 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1216,10 +1216,11 @@ static void zram_free_page(struct zram *zram, size_t index) static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, struct bio *bio, bool partial_io) { - int ret; + struct zcomp_strm *zstrm; unsigned long handle; unsigned int size; void *src, *dst; + int ret; zram_slot_lock(zram, index); if (zram_test_flag(zram, index, ZRAM_WB)) { @@ -1250,6 +1251,9 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, size = zram_get_obj_size(zram, index); + if (size != PAGE_SIZE) + zstrm = zcomp_stream_get(zram->comp); + src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); if (size == PAGE_SIZE) { dst = kmap_atomic(page); @@ -1257,8 +1261,6 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, kunmap_atomic(dst); ret = 0; } else { - struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp); - dst = kmap_atomic(page); ret = zcomp_decompress(zstrm, src, size, dst); kunmap_atomic(dst);