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 9997AC13D; Thu, 30 Jan 2025 14:00:56 +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=1738245656; cv=none; b=t/tzene4OohaMH/IEo+kIhdwYJ/uVbU+YFAZeGFc7i48MN0Q411KeSXRx2duTStwDArkTCBjVJnyh5UMNHk3mfqnfxprtgMtxLR0mjSnvhh2czjvsqtlO7cVYz6fdLg5Ma+BpCq22D7pBcQkVORoKgqnW6grJdFAYtY4gIUJB4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738245656; c=relaxed/simple; bh=jeVcmipITSUhUbMPN/LFjwE+WkvhVeNb2kpHArvt0a4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OhGuzucSiHufTdgLa9sSd8H5VyRTQtXjgrZbtMQ9oTf7/MSmoYn3roxhbeVfqgSa5hD6tWLjhFOq/OmnaUg0AuajUTsjlmHpQrUaSy+HD1CE/3rAngJ/KRxO8bN+O0AtT2Pcmzt5D/lV6rs3KcwOMMQJajCOb5eN1Elv/RorzhM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Rr2JpQuG; 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="Rr2JpQuG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26C51C4CED2; Thu, 30 Jan 2025 14:00:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1738245656; bh=jeVcmipITSUhUbMPN/LFjwE+WkvhVeNb2kpHArvt0a4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Rr2JpQuGNkbcIS0ri9S6UuvqmZgmiH9U/mvbUmBY66kdwQaa5goSn7RwsTRJ70BDM pKZEaUZ4shq+3TncaOmErijgt9sp2jB1tV6cRxdz9T309YzNtucabUQrZoBDEGA1uk F7HTVCuZBev0nHU4J4in2QWTSVus67YNFBDUGlEU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yosry Ahmed , Chengming Zhou , Johannes Weiner , Nhat Pham , Andrew Morton Subject: [PATCH 6.12 16/40] mm: zswap: move allocations during CPU init outside the lock Date: Thu, 30 Jan 2025 14:59:16 +0100 Message-ID: <20250130133500.361454546@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250130133459.700273275@linuxfoundation.org> References: <20250130133459.700273275@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yosry Ahmed commit 779b9955f64327c339a16f68055af98252fd3315 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- mm/zswap.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) --- a/mm/zswap.c +++ b/mm/zswap.c @@ -815,15 +815,15 @@ static int zswap_cpu_comp_prepare(unsign { 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)); @@ -831,21 +831,25 @@ static int zswap_cpu_comp_prepare(unsign 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 @@ -854,15 +858,17 @@ static int zswap_cpu_comp_prepare(unsign 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; }