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Wed, 18 Mar 2026 21:05:59 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:13e1:7517:52f3:cfc8]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35bc6017492sm1281973a91.5.2026.03.18.21.05.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 21:05:59 -0700 (PDT) Date: Thu, 19 Mar 2026 13:05:55 +0900 From: Sergey Senozhatsky To: Sergey Senozhatsky Cc: Andrew Morton , Minchan Kim , Brian Geffon , Richard Chang , linux-block@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] zram: do not slot_free() written-back slots Message-ID: References: <20260319034912.1894770-1-senozhatsky@chromium.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260319034912.1894770-1-senozhatsky@chromium.org> As a side note: On (26/03/19 12:44), Sergey Senozhatsky wrote: > - slot_free(zram, index); [..] > - if (huge) > - set_slot_flag(zram, index, ZRAM_HUGE); Original code had a bug. slot_free() would decrement ->huge_pages, then writeback completion would restore the HUGE flag, so when slot would get freed for real slot_free() would decrement ->huge_pages again, leading to underflow.