From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E6CB81FC8 for ; Mon, 20 Jan 2025 13:38:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737380296; cv=none; b=E1fw//Y8+bVFHqPY6IEt4/Hdl7AX9SwwNuGUYKP7m88aT/6w0A22mlV42vgjgYPNUdB7yT/LSw7dQqhHcuWSrCGAAKAijJ/AsKz1E3MbcZQcf2LCbA2ui/qYIEvCSd2gTeadVWoSDsWQcOMx+bEFPot8VcyjPCTe1zEtVqrJzCU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737380296; c=relaxed/simple; bh=7XLQMcYYMnEUKzfDVtg6XnrHBL1Pj4KjNvkuzEB8wOs=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=TW/aSexfqf7ajHvJDeW6+fgxaPddxJFdoFpvwCwaslOWo5Ny0XOZsQzNhBzkr+0RJRUZTaykwmGYwZ00tPelBRdqlso1Z3MOTP7A5FfGFhwfPkXd4OG70A2Uw2rQn5/idRUCt+0UKfncFbF4qh3/lhqKxto6pgjaemHab6bh1+g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oa+p6xRz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="oa+p6xRz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6813DC4CEDD; Mon, 20 Jan 2025 13:38:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1737380295; bh=7XLQMcYYMnEUKzfDVtg6XnrHBL1Pj4KjNvkuzEB8wOs=; h=Subject:To:Cc:From:Date:From; b=oa+p6xRzjAqvjVpelCiq7ijZZ8HVMLDXhK0rou/LPKPPm85FBDMWiyqfIPFBTSC4A Wco0LsSDIHCAcrYlCUgMTWA81WQPgRBGLPtdC6Rpejo7e5SsMlrXppn1CAUjgxEjz4 ePzKOpaGhpkC+p4v6gn7qYg7EtYDZ4RON3lbOPZ4= Subject: FAILED: patch "[PATCH] mm: zswap: move allocations during CPU init outside the lock" failed to apply to 6.1-stable tree To: yosryahmed@google.com,akpm@linux-foundation.org,chengming.zhou@linux.dev,hannes@cmpxchg.org,nphamcs@gmail.com,stable@vger.kernel.org Cc: From: Date: Mon, 20 Jan 2025 14:38:02 +0100 Message-ID: <2025012002-overstep-numbness-cf60@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 6.1-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-6.1.y git checkout FETCH_HEAD git cherry-pick -x 779b9955f64327c339a16f68055af98252fd3315 # git commit -s git send-email --to '' --in-reply-to '2025012002-overstep-numbness-cf60@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 779b9955f64327c339a16f68055af98252fd3315 Mon Sep 17 00:00:00 2001 From: Yosry Ahmed Date: Mon, 13 Jan 2025 21:44:58 +0000 Subject: [PATCH] mm: zswap: move allocations during CPU init outside the lock In zswap_cpu_comp_prepare(), allocations are made and assigned to various members of acomp_ctx under acomp_ctx->mutex. However, allocations may recurse into zswap through reclaim, trying to acquire the same mutex and deadlocking. Move the allocations before the mutex critical section. Only the initialization of acomp_ctx needs to be done with the mutex held. Link: https://lkml.kernel.org/r/20250113214458.2123410-1-yosryahmed@google.com Fixes: 12dcb0ef5406 ("mm: zswap: properly synchronize freeing resources during CPU hotunplug") Signed-off-by: Yosry Ahmed Reviewed-by: Chengming Zhou Cc: Johannes Weiner Cc: Nhat Pham Cc: Signed-off-by: Andrew Morton diff --git a/mm/zswap.c b/mm/zswap.c index 30f5a27a6862..b84c20d889b1 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -820,15 +820,15 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) { struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); - struct crypto_acomp *acomp; - struct acomp_req *req; + struct crypto_acomp *acomp = NULL; + struct acomp_req *req = NULL; + u8 *buffer = NULL; int ret; - mutex_lock(&acomp_ctx->mutex); - acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); - if (!acomp_ctx->buffer) { + buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); + if (!buffer) { ret = -ENOMEM; - goto buffer_fail; + goto fail; } acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); @@ -836,21 +836,25 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) pr_err("could not alloc crypto acomp %s : %ld\n", pool->tfm_name, PTR_ERR(acomp)); ret = PTR_ERR(acomp); - goto acomp_fail; + goto fail; } - acomp_ctx->acomp = acomp; - acomp_ctx->is_sleepable = acomp_is_async(acomp); - req = acomp_request_alloc(acomp_ctx->acomp); + req = acomp_request_alloc(acomp); if (!req) { pr_err("could not alloc crypto acomp_request %s\n", pool->tfm_name); ret = -ENOMEM; - goto req_fail; + goto fail; } - acomp_ctx->req = req; + /* + * Only hold the mutex after completing allocations, otherwise we may + * recurse into zswap through reclaim and attempt to hold the mutex + * again resulting in a deadlock. + */ + mutex_lock(&acomp_ctx->mutex); crypto_init_wait(&acomp_ctx->wait); + /* * if the backend of acomp is async zip, crypto_req_done() will wakeup * crypto_wait_req(); if the backend of acomp is scomp, the callback @@ -859,15 +863,17 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &acomp_ctx->wait); + acomp_ctx->buffer = buffer; + acomp_ctx->acomp = acomp; + acomp_ctx->is_sleepable = acomp_is_async(acomp); + acomp_ctx->req = req; mutex_unlock(&acomp_ctx->mutex); return 0; -req_fail: - crypto_free_acomp(acomp_ctx->acomp); -acomp_fail: - kfree(acomp_ctx->buffer); -buffer_fail: - mutex_unlock(&acomp_ctx->mutex); +fail: + if (acomp) + crypto_free_acomp(acomp); + kfree(buffer); return ret; }