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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vfsMO-00000005fdK-2Wct; Wed, 14 Jan 2026 04:19:56 +0000 Date: Wed, 14 Jan 2026 04:19:56 +0000 From: Matthew Wilcox To: wang.yaxin@zte.com.cn Cc: akpm@linux-foundation.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, david@kernel.org, vbabka@suse.cz, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xu.xin16@zte.com.cn, yang.yang29@zte.com.cn, fan.yu9@zte.com.cn, he.peilin@zte.com.cn, tu.qiang35@zte.com.cn, qiu.yutan@zte.com.cn, jiang.kun2@zte.com.cn, lu.zhongjun@zte.com.cn Subject: Re: [PATCH linux-next] mm/madvise: prefer VMA lock for MADV_REMOVE Message-ID: References: <202601141124178748cM66DJW2fzNea7Uym1mG@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202601141124178748cM66DJW2fzNea7Uym1mG@zte.com.cn> X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4B02DC000D X-Stat-Signature: yyqrgzyqhp6fh9isrs6rhd56j74ke1d3 X-HE-Tag: 1768364400-55116 X-HE-Meta: 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 2szClgsL OqAVPA4hgIVvekbgxFKSJFOuqoVMWkOl/wed15daehUWNWKDKdrzolXOtOAoG1lcXU+YwteGmPrucb/FQHexNq0NeKKH8GFt2UdCI9ALp1JoYibQkqlVFwD/KUoH2OLu0fpvxhVjfo8yi/TLAturpXboMjzqqkgKBej3ppI4CR0v3M2LAL/pzFK3FVYCL+ZIkhd4S3IVBJTH8oQqvjk7scCvYy3cPl7kDx1OosXyIdQP2TO4oCWc2O3wYLeq98PuA7spTaXmzJxJLWnelvthTs19nUuC/J2bAHtw642W1rEFSHCDo3ijjRwLt24KBTxnLwpE+iuoHq/bspWyDM6C4kAjESy+TN6tmrSnoFRJtJDV6gNLUiJbzr06rwJOU2aEZNTb0 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 Wed, Jan 14, 2026 at 11:24:17AM +0800, wang.yaxin@zte.com.cn wrote: > From: Jiang Kun > > MADV_REMOVE currently runs under the process-wide mmap_read_lock() and > temporarily drops and reacquires it around filesystem hole-punching. > For single-VMA, local-mm, non-UFFD-armed ranges we can safely operate > under the finer-grained per-VMA read lock to reduce contention and lock > hold time, while preserving semantics. Oh, and do you have any performance measurements? You're introducing complexity, so it'd be good to quantify what performance we're getting in return for this complexity. A real workload would be best, but even an artificial benchmark would be better than nothing.