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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uklC4-0000000GrcX-0zn3; Sat, 09 Aug 2025 15:09:12 +0000 Date: Sat, 9 Aug 2025 16:09:12 +0100 From: Matthew Wilcox To: "Subrata Nath (Nokia)" Cc: Andrew Morton , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm: prevent RCU stalls in kswapd by adding cond_resched() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: csunh4aigxqzmdrrjjn7rbwc19ydyoyn X-Rspam-User: X-Rspamd-Queue-Id: 170C84000E X-Rspamd-Server: rspam02 X-HE-Tag: 1754752154-866742 X-HE-Meta: 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 5YELOJne VUR83+sbuOXO8a9YFvBjd2dZOG5IgdRTvGxFZbASv9ngjTWLd1pscWdDRN+LlZtM0nweEgm5bH4WhrWyXeHIs85XpM698/kjWXhn+HEtvt2Kf0s9i9sTu1ScNA+I/79P561lcWJXqZyMVBpfgk5ruSAJCtiHWUQ/eCjEP6ZGkyiix88FtaxRlSl2QBbCkttC9e2aphlhJveVXEWxJRFUoe8dnNjKre4TTxlkMv+1AVRxWV0Y13fr1ipHsWhTxKHO/pCZB1s6/TbL557D00HNo4/gEfEWzMc6udlLw 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 Sat, Aug 09, 2025 at 11:59:16AM +0000, Subrata Nath (Nokia) wrote: > Fix this by adding cond_resched() after all spinlock release points > in page_vma_mapped_walk() and in the main loop of shrink_zones(). > These calls, placed outside spinlock-held sections, allow voluntary > scheduling and ensure timely quiescent state reporting, avoiding > prolonged RCU stalls. No. We're removing cond_resched(). See https://lore.kernel.org/linux-mm/87cyyfxd4k.ffs@tglx/ and many many other emails over the past few years.