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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776332118; bh=qzx86yIYEM/GemLvFCh/lwiEzuYxSCpGtYSGjiBaBAY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=V2OY/WXd/jcvmTN+lN0/LtgwDqPt1EqOT/yVI1PrNnh/fI7foPgvgxdGx54kwKGKN E/2Ggvpn6n2OZ7eyYF3SzeoST/lwZ8wYWbdjUB0YidY5dw+8qU+W0VoGe/tIZGXyvK W1AIYLxoYYnU1LFW965p0UTthgAyMyiObDfnDoG/NpMwVwRxd3j5G0cRxPApZEW5y9 Y5NluBS9bpV12u/Vj4npXYp36Jb7M1zF50aFMy/lPFg8eYGFSlO9cCFffS3jdo0ZrQ bEgwNIdp2af7qzaBYnor+rcBtHDPBYCEOTxmQzmxr4AaoPeH4ebZ69LysVK79NtLWu 3YYlqzcFxQBAg== From: Pratyush Yadav To: Chenghao Duan Cc: Pratyush Yadav , pasha.tatashin@soleen.com, rppt@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jianghaoran@kylinos.cn Subject: Re: [PATCH v3 2/7] mm/memfd_luo: optimize shmem_recalc_inode calls in retrieve path In-Reply-To: <20260410014537.GA28528@chenghao-pc> (Chenghao Duan's message of "Fri, 10 Apr 2026 09:45:37 +0800") References: <20260326084727.118437-1-duanchenghao@kylinos.cn> <20260326084727.118437-3-duanchenghao@kylinos.cn> <2vxz8qb5hbgz.fsf@kernel.org> <20260410014537.GA28528@chenghao-pc> Date: Thu, 16 Apr 2026 09:35:14 +0000 Message-ID: <2vxzse8v6yel.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 12E87120009 X-Rspamd-Server: rspam12 X-Stat-Signature: xixof7nku98dzbwcx5e1dg53bcxtjm87 X-Rspam-User: X-HE-Tag: 1776332118-160340 X-HE-Meta: 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 d8dKrGZl iEnV3y113Zj6EN/RygizHKd0vtkWG90VD/WDSNQec9H/anG4Kd1dArbOqwLwZIAeN9HVg3RkTwLeQd9gAfEL1S17OjZzatF1li2vWoWWST1LzR2muX0Gc/iKSTfUNMJT2Ufm0cdAHQkTPWg8RsbUnts05TWnOPRZN/adlEE4cYeojobf5feR5QtR5mf7gntICvtb+Wc7QlK5VJ57KQOCMkvsqn935DUw+7TkvjU88q0G//UKQhjdlYoyp9fFul807w++1tEo+1/V2wgOharHijqjkH6pbjyUBRoH4ouCcmmMB1d0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 10 2026, Chenghao Duan wrote: > On Thu, Apr 02, 2026 at 11:02:04AM +0000, Pratyush Yadav wrote: >> On Thu, Mar 26 2026, Chenghao Duan wrote: >> >> > Move shmem_recalc_inode() out of the loop in memfd_luo_retrieve_folios() >> > to improve performance when restoring large memfds. >> > >> > Currently, shmem_recalc_inode() is called for each folio during restore, >> > which is O(n) expensive operations. This patch collects the number of >> > successfully added folios and calls shmem_recalc_inode() once after the >> > loop completes, reducing complexity to O(1). >> > >> > Additionally, fix the error path to also call shmem_recalc_inode() for >> > the folios that were successfully added before the error occurred. >> > >> > Reviewed-by: Pasha Tatashin >> > Signed-off-by: Chenghao Duan >> >> Reviewed-by: Pratyush Yadav >> >> BTW, can we also do the same for shmem_inode_acct_blocks() it the call >> to it can also be aggregated in the same way? You don't have to do it in >> this series, but possibly as a follow up. >> > Thanks for pointing that out. > > We can move shmem_recalc_inode() outside the loop for aggregation, as it > performs a single inode state update for the folios. > > In contrast, shmem_inode_acct_blocks() is a validation step for resource > reservation, quota, and block accounting. Since it can fail on its own, > aggregating it outside the loop would complicate the error handling and > rollback paths, especially when only a subset of folios have been restored. Okay, fair enough. Thanks for looking into it. -- Regards, Pratyush Yadav