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Wed, 07 Jan 2026 17:17:47 -0800 (PST) Received: from google.com ([2a00:79e0:2031:6:7bef:7c13:79b4:e9de]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3c3a507sm60054065ad.3.2026.01.07.17.17.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jan 2026 17:17:46 -0800 (PST) Date: Thu, 8 Jan 2026 10:17:41 +0900 From: Sergey Senozhatsky To: Yosry Ahmed Cc: Sergey Senozhatsky , Andrew Morton , Nhat Pham , Minchan Kim , Johannes Weiner , Brian Geffon , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv2 2/2] zsmalloc: simplify read begin/end logic Message-ID: References: <20260107052145.3586917-1-senozhatsky@chromium.org> <20260107052145.3586917-2-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 357A38000B X-Stat-Signature: 4ncj5jyabhhwdx8nebbtazh3rjfhbj7f X-Rspam-User: X-HE-Tag: 1767835068-529671 X-HE-Meta: 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 bihulRhI EI9A/KLFrGJt5Vtg= 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 (26/01/07 19:03), Yosry Ahmed wrote: > On Wed, Jan 07, 2026 at 02:21:45PM +0900, Sergey Senozhatsky wrote: > > From: Yosry Ahmed > > While I appreciate this, I think for all intents and purposes this patch > should be credited to you, it's different from the diff I said as it > applies on top of your change. > > If you're feeling really generous, I think Suggested-by or > Co-developed-by + Signed-off-by is sufficient :) Okey-dokey Co-developed-by: Yosry Ahmed > > When we switched from using class->size (for spans detection) > > to actual compressed object size, we had to compensate for > > the fact that class->size implicitly took inlined handle > > into consideration. In fact, instead of adjusting the size > > of compressed object (adding handle offset for non-huge size > > classes), we can move some lines around and simplify the > > code: there are already paths in read_begin/end that compensate > > for inlined object handle offset. > > I think the commit log is not clear in isolation. > > How about something like this: > > zs_obj_read_begin() currently maps or copies the the compressed object > with the prefix handle for !ZsHugePage case. Make the logic clearer and > more officient by moving the offset of the object in the page after the > prefix handle instead, only copying the actual object and avoiding the > need to adjust the returned address to account for the prefix. > > Adjust the logic to detect spanning objects in zs_obj_read_end() > accordingly, slightly simplifying it by avoiding the need to account for > the handle in both the offset and the object size. Looks good to me. Andrew, can we trouble you with commit message update or should I resend?