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Mon, 16 Mar 2026 18:48:19 -0700 (PDT) From: "Kanchana P. Sridhar" To: hannes@cmpxchg.org, yosry@kernel.org, nphamcs@gmail.com, chengming.zhou@linux.dev, akpm@linux-foundation.org, kanchanapsridhar2026@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: herbert@gondor.apana.org.au, senozhatsky@chromium.org Subject: [PATCH v2 1/2] mm: zswap: Remove redundant checks in zswap_cpu_comp_dead(). Date: Mon, 16 Mar 2026 18:48:01 -0700 Message-Id: <20260317014802.27591-2-kanchanapsridhar2026@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260317014802.27591-1-kanchanapsridhar2026@gmail.com> References: <20260317014802.27591-1-kanchanapsridhar2026@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3E94C120010 X-Stat-Signature: scjzeiu5ywy4kr5bj68y6i6npgwucwps X-HE-Tag: 1773712100-541648 X-HE-Meta: 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 rU9M1sPL qacS4SeSrGjXHjaUoIhl162tGdvkdPzGw0LaN6UvRnjEYgBxVuPVlyt3abp4RwuFABkLZEbAB7xnx7aJQNYD7n5lvLjii+WRwTeVa+Ft40gWyDs0Z08TtLcVo4b6a8PkyDPgckBhmgEqEDzE3bGPYqXjgw4xXmFnnE5wIiK8R3l7FBiYKsxK+a5i4DpkecQZkRlKt7psqXyeJi3v4Z3wKnW/CBNxu8qXNW6jk0dDbsFoOKMYeAaUEnKHNeyIp1alwNXsWbJ2LVYR3c3m3MbjoMv9OA6rNNo3NzA33b3q3kRWGF+uaXcerA7zBoOIgQbGcO4uJ/pU3DPATC3mFOwuGNvV8zZgjmeOyDEvHiWyBukgeWDnc2qrWJEpewBbcEYOo7IrPbbtwm46R6HCMj1cANmOYC9oz8pmCbRdGFukdOGrVkD8nefuHiMDPnqYp+uauxByDpA7q5SUruWMEQT5C8J8rmb9OO9mGQcOfM+TVhmz2RI8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: There are presently redundant checks on the per-CPU acomp_ctx and it's "req" member in zswap_cpu_comp_dead(): redundant because they are inconsistent with zswap_pool_create() handling of failure in allocating the acomp_ctx, and with the expected NULL return value from the acomp_request_alloc() API when it fails to allocate an acomp_req. Fix these by converting to them to be NULL checks. Add comments in zswap_cpu_comp_prepare() clarifying the expected return values of the crypto_alloc_acomp_node() and acomp_request_alloc() API. Suggested-by: Yosry Ahmed Signed-off-by: Kanchana P. Sridhar --- mm/zswap.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index bdd24430f6ff..8ac38f1d0469 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -749,6 +749,10 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) goto fail; } + /* + * In case of an error, crypto_alloc_acomp_node() returns an + * error pointer, never NULL. + */ acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); if (IS_ERR(acomp)) { pr_err("could not alloc crypto acomp %s : %pe\n", @@ -757,6 +761,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) goto fail; } + /* acomp_request_alloc() returns NULL in case of an error. */ req = acomp_request_alloc(acomp); if (!req) { pr_err("could not alloc crypto acomp_request %s\n", @@ -802,7 +807,7 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) struct crypto_acomp *acomp; u8 *buffer; - if (IS_ERR_OR_NULL(acomp_ctx)) + if (!acomp_ctx) return 0; mutex_lock(&acomp_ctx->mutex); @@ -817,8 +822,11 @@ static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) /* * Do the actual freeing after releasing the mutex to avoid subtle * locking dependencies causing deadlocks. + * + * If there was an error in allocating @acomp_ctx->req, it + * would be set to NULL. */ - if (!IS_ERR_OR_NULL(req)) + if (req) acomp_request_free(req); if (!IS_ERR_OR_NULL(acomp)) crypto_free_acomp(acomp); -- 2.39.5