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Tue, 31 Mar 2026 11:34:05 -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 v3 1/2] mm: zswap: Remove redundant checks in zswap_cpu_comp_dead(). Date: Tue, 31 Mar 2026 11:33:50 -0700 Message-Id: <20260331183351.29844-2-kanchanapsridhar2026@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260331183351.29844-1-kanchanapsridhar2026@gmail.com> References: <20260331183351.29844-1-kanchanapsridhar2026@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 91mcct9uifutkhy733m69or43hp6etfp X-Rspamd-Queue-Id: 5E62514000E X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1774982047-750035 X-HE-Meta: U2FsdGVkX19HRNNyhdxuyXODeSnRFoQZUpIAIASsiPQc5WDD7F6hvg0HtInxAlVaDzFs+ci68zVJWhxcWjFkBWL6GGPxpqmy+Xh7Oa1hWIBOSjAsdbWYwj8fprC5DTj5xPPY8xthRfYBj8dNHvtbVwDrJu2aSNITSpjAacaWhV+AImLiihWAuDTUCjEy8DgQi1vLW0zwxVP8eR0yA+Hz8Ip7ZW5658vS4+OqWo0XBg7eBTpkDLG6Weq2QZnYgWvstrUqneH9E2iGMhXkASNkuv5AOX1HsYny78maJwa1K+jZEDoUkb3radGkPJFbRi3Uwb8lJT+dBydu0DoqPZrDE8iM6AqbGjcYpe6MGU7kPjqe758Caf5sstwksYhuDHN9958F2tOB8BdLRIKJpMSIAaAnm8JgDUR1ibGQLkVQT1oSOv45gAeEma4PYnoyeP324dadMyhO+5YQD9n9y4yd6JVCCWGh7RJfAOMVcMLkHt0NPKKp16q/yGyqdoHxiEhea9I6ym4PcDdWwpOcval2V4xbgK5OMNIpy3prtnzBRpXCxGZhLqw6tzrVRBmG6jnp1lkCKCZRjrK7kyq/B4fEkdyg3KVyoqNR/GbBFxIuRMdBNLoSks3BcDne1ia1HOCdEnQb7DZ6lmiQ3mS0OT51OIv74pgTQ2+Qq8+Fcc4PXEU0qm2Nw1pe9fgMUgcdyrnZDGqq6G5Msac+vQr91++AlBKL8hbyhU9frCTGMfoimoRni+LCdLwSQeFtid23/tx80cw22ijjzq0mn/LusJQbhnLHYHBxAfpMIY+xjcrHID3r9uf+J+zb+sAFRxLiOajjf9iCLlJNTC36SLb/5Ha1T/otVN7/fmLEAIbVY7ok3vuHkk168MD6SQoRnzhg6i5ZtsyPN8MVjKxMh8NJ+srNNirMVAz5SUb81FKiHmiUQ9vz50d+ZR8wHg8hDAc8+Xsf0A3z6O70raU0aVRlYMm 38XEOlRZ DKs2PC4oWL2CDhk5tzbxQ7TeuHe5YKVNRQr/Upy34MrIiVoKPk54WcOJ1dqLT5WvxrDuP4Qj/AnU4+6mm5ZmOMV4X9/RpyZCUfTPCM7RPJWLpaKuGTeECoKn2XU7onA2q1UiHTNIV7LE8KhsgS8TSHjIQAj++K8nnuoX7vE/XdL4h1ovpmOM/ImiWj9b+vAOW6jAsPL0V5wH0OiAITw37xq67sCCfxatMcgl6CBF27+NGLFRkJr1Kho61qDuoNyftbE13a1UFvnRkv6iVVg4xouSZ9+Sr7qBRU48aS/trNClqNvPeqXAvS51qeLZlUaM7LfI8Ves2nC+RvuAtkbyO98mW+vgJNUcI64VOfWvYjEERvV/J5nNocWJfNvoXMj54gRhb0PL4K4JswRNhHdpdbOUHBh7zkWoTra2UYJncoHAq0SdRCTwICzjGQLE4zqYSaxj/k2ZlfSXSfCAkZvrKgZ9sn3ydEpfSweYmfUjgzWVIZfc= 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 Acked-by: Yosry Ahmed --- mm/zswap.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index 4f2e652e8ad3..c59045b59ffe 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