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Mon, 17 Nov 2025 23:50:04 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:beba:22fc:d89b:ce14]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7b92714e298sm15568611b3a.34.2025.11.17.23.50.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Nov 2025 23:50:04 -0800 (PST) Date: Tue, 18 Nov 2025 16:49:58 +0900 From: Sergey Senozhatsky To: Yuwen Chen Cc: senozhatsky@chromium.org, akpm@linux-foundation.org, bgeffon@google.com, licayy@outlook.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, minchan@kernel.org, richardycc@google.com Subject: Re: [PATCH] zram: Fix the issue that the write - back limits might overflow Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: osxrdqajx4799ripw18xb1z66pwn696d X-Rspam-User: X-Rspamd-Queue-Id: BC06A1C000A X-Rspamd-Server: rspam01 X-HE-Tag: 1763452205-275314 X-HE-Meta: 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 eCfdD4K/ v0L/txgBMJMQs7UMB6TvRGpAjFpeZ3iav3dAISJ2u7uMOy8/b+8HkM3ltkYr8Rxi9WJJvfY/FjcCtw5a2AmzCm1ZbHb9qVFOGzQ9nQanIt5cP2/bQo6VJhBXL/+tBwaGyR8V1WTie218wbxSfh6I3tsY7jEQPqBT0o3Z2klSXe+r68yI9i7NDdF6ID58iYe4rxQtOAriUeX8VfeQBXBDQ/mH6QfhTXDA7N36Eqv7Wj03ICAffOy9aafCk7JvEAT0Sx34lSaGLRR0mFs6UivsDiPwDJwrBv6iscnL1YG4KGTlBoQJA4SvZHUr9Aosyvn0STMEERWK9Z/xn5nZBuIYnBkyudwdncSbzYZtizuVD0XErCj7uCQiLFenFCTKsog+NokQtyDX8Rr0+CnwcAXmq4PCwUPea1xZR3aW4xgtSIWzt1CQSR1wta+HR+g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On (25/11/18 15:39), Yuwen Chen wrote: > Since the value of bd_wb_limit is an unsigned number, when the > page size is larger than 4 KB, it may cause an out-of-bounds situation. > > This patch fixes the issue by limiting bd_wb_limit to be an > integer multiple of PAGE_SIZE / 4096. > > Fixes: 1d69a3f8ae77e ("zram: idle writeback fixes and cleanup") > Signed-off-by: Yuwen Chen > --- > drivers/block/zram/zram_drv.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index 4f2824a..4ecf2e7 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -562,6 +562,7 @@ static ssize_t writeback_limit_store(struct device *dev, > if (kstrtoull(buf, 10, &val)) > return ret; > > + val = val & (~((1UL << (PAGE_SHIFT - 12)) - 1)); > down_read(&zram->init_lock); > spin_lock(&zram->wb_limit_lock); > zram->bd_wb_limit = val; This patch is against unfixed writeback_limit_store() function, it will need to be resubmitted once [1] lands. [1] https://lore.kernel.org/linux-mm/20251118073000.1928107-1-senozhatsky@chromium.org