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b=kjHUXCdimWNssHiG84hgXyOpxr4RDdpWMi+6H9URWbaXrRuJAML2fXUQ4z8D/OP0E SCdk36sajdWZ3RdYiT1zKeGEZ0E8P4saW1sMHZheKdonIo4YJdEGC9FoiZjFg84i5e B9jPLtZonTsACdUCJlHgqfgfY+XpkU1Nxb9mg1/c= Date: Tue, 22 Sep 2026 18:39:21 -0700 From: Andrew Morton To: Catalin Marinas Cc: Breno Leitao , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH 2/2] mm: kmemleak: scan the struct page array in MAX_SCAN_SIZE batches Message-Id: <20260922183921.b30bc1c3ba9443e021910851@linux-foundation.org> In-Reply-To: References: <20260921-b4-kmemleak-page-scan-v1-0-fb97d4801b3a@debian.org> <20260921-b4-kmemleak-page-scan-v1-2-fb97d4801b3a@debian.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E708C80004 X-Stat-Signature: 1xcpuunhinsb6qdwe5hofoy93yx46cif X-HE-Tag: 1790127562-539364 X-HE-Meta: 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 xhjNWc90 Pti3QmuTLE8FzZmdjsW49QGdf3iSkq5O2LL6JmQeK5fF0H1K1oyfMQXaRmJ48fxjWC1NRk9b2f4Bbt90cnATCq4Zhn8g9vHSMQLkD+RsDA3o78FEuMlgM7MtCQyQArCH2/3RJ6LkBYIy6MKYzqfQmiIPeILr48IvIgba+zkfpjP0luV/F87c2xtyX0x1/hpTbu5FbPKbzsB/PL0XyzrZdJ4h6eGW2ODJ08jSAmjLdrVhdAle6ktBXE86zAVz54N6+sHOQgWFl5qBwbYE1rmRb5hPIVt8JufAo49cSQ8KbKG7UkmVU/Cw/VtcE4zDbbd+GCKwne7+1G7OLPHEAUjfz6H5GWRqLG1AAI9NV Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 22 Sep 2026 10:51:46 +0100 Catalin Marinas wrote: > On Mon, Sep 21, 2026 at 05:30:27AM -0700, Breno Leitao wrote: > > scan_zone_pages() scans the struct page array one page per scan_block() > > call: > > > > if (scan_block(page, page + 1, NULL)) > > > > scan_block() takes kmemleak_lock with interrupts disabled for the > > duration of the call, so this acquires the lock once per online PFN to > > scan a single struct page. > > > > Gather runs of adjacent eligible struct pages and pass each run to > > scan_block() in one call, capped at MAX_SCAN_SIZE. > > > > The longest kmemleak_lock is now held is MAX_SCAN_SIZE worth of words, > > Remove an 'is'. That was actually correct, but it doesn't read well. > Also, MAX_SCAN_SIZE worth of bytes rather than words. edited, thanks. How's this? : The longest kmemleak_lock hold duration is now MAX_SCAN_SIZE worth of : bytes. The same bound scan_large_block() already applies to the data : sections and the per-CPU areas.