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Wed, 17 Dec 2025 08:47:12 -0800 (PST) Sender: Guenter Roeck Date: Wed, 17 Dec 2025 08:47:12 -0800 From: Guenter Roeck To: Joshua Hahn Cc: Andrew Morton , Daniel Palmer , Brendan Jackman , Johannes Weiner , Michal Hocko , Suren Baghdasaryan , Vlastimil Babka , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/page_alloc: restore 0-handling to zone_set_pageset_high_and_batch Message-ID: References: <20251217060505.681923-1-joshua.hahnjy@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251217060505.681923-1-joshua.hahnjy@gmail.com> On Tue, Dec 16, 2025 at 10:05:03PM -0800, Joshua Hahn wrote: > Commit 2783088ef24e ("mm/page_alloc: prevent reporting pcp->batch = 0") > moved the error handling (0-handling) of zone_batchsize from its > callers to inside the function. However, the commit left out the error > handling for the NOMMU case, leading to deadlocks on NOMMU systems. > > Since in the NOMMU case the reported-to-user batchsize should still be 0, > we would only like the error handling to exist in the callsites that > set the internal value for the zone (i.e. zone_set_pageset_high_and_batch). > > Restore max(1, zone_batchsize(zone)) to the callsite to prevent errors > on NOMMU systems. > > Fixes: 2783088ef24e ("mm/page_alloc: prevent reporting pcp->batch = 0") > Reported-by: Daniel Palmer > Closes: https://lore.kernel.org/linux-mm/CAFr9PX=_HaM3_xPtTiBn5Gw5-0xcRpawpJ02NStfdr0khF2k7g@mail.gmail.com/ > Reported-by: Guenter Roeck > Closes: https://lore.kernel.org/all/42143500-c380-41fe-815c-696c17241506@roeck-us.net/ > Signed-off-by: Joshua Hahn For m68k:mcf5208evb boot tests with qemu: Tested-by: Guenter Roeck Guenter