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Wed, 11 Mar 2026 01:27:58 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:93a4:8281:fe98:426a]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35a02e19708sm1947257a91.3.2026.03.11.01.27.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 01:27:57 -0700 (PDT) Date: Wed, 11 Mar 2026 17:27:54 +0900 From: Sergey Senozhatsky To: Andrew Morton Cc: Minchan Kim , Brian Geffon , linux-block@vger.kernel.org, linux-mm@kvack.org, gao xu , Sergey Senozhatsky Subject: Re: [PATCH] zram: do not permit params change after init Message-ID: References: <20260310060407.1133800-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260310060407.1133800-1-senozhatsky@chromium.org> X-Rspamd-Queue-Id: 6C1591C000A X-Stat-Signature: wq1gfwusicygwhpqsgnxfhmgo9fgrpsi X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773217679-846593 X-HE-Meta: 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 zRgDJPZe MmtxjvQvJTbpoaubYf6qgVP/m0SlBcXSsQSzkrfaK9af6P6QYnFIRp8XCEuvsyXAIYERBjV8pL5sTJmxkd/W+hePWsCHfUomaQ4+i0fSOrMQhR9pHBuX+JeI2Kmv0XJRNMuoOs+ROQJXx7jB2ojwLGpcTm7cI5j4UviBmFDxCsJem1ScA0rbWhlG6+rFFY+4+gNEhXcnYQ3CjiRk08lpRkl+UaL857uZRqn3+JPdJdcKhj8ylrfqzZS7m0GPojf8wQgPWCQpVmjTWRX+3Pmhtf/2TAImtISvoJm+hfWh1WugnNwe88TA805K64GnwYlyWKg9+Vb/NSRzlYorFKUUabwwmlon4YE/KTtfg6k10JURYDVbWXWd2wt0+EIO8AMv0Jo/QGmWvqkjsgCCsHv+yEaTORw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (26/03/10 15:01), Sergey Senozhatsky wrote: > First, algorithm_params_store(), like any sysfs handler, > should grab device init lock. > > Second, like any write() sysfs handler, it should grab > device init lock in exclusive mode. > > Third, it should not permit change of algos' parameters > after device init, as this doesn't make sense - we cannot > compress with one C/D dict and then just change C/D dict > to a different one, for example. > > Fixes: 4eac932103a5d ("zram: introduce algorithm_params device attribute") > Cc: gao xu > Signed-off-by: Sergey Senozhatsky Andrew, I will include this patch into v2 of the zram fixups, can you please drop it for now? We need to protect algo lookup path as well, which accesses ->comp_algs. I'll fix that in v2.