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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766655175; bh=crIs7Vpzht/pnJ1aDRt6pQoB0tVv3wmg1UPYo0oHvb8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=jFxu+XO1h+7qVufOEkkeqYJ+y8+ggI/EjXBUiY3/m1mhMJxUKl5bfL1k03shi5Yqp E/ms3S/D3iMl+EDwHTlA2nFYMmWIjPZjxq96aUOCbpTwFo4YoOF243vMMb2Fs72paF kHChZbjIfDArAhQx6T3kZ36v5u0TWc3Tv+DAqgS8r9bW0zC/ZfFDyGRHRpuDyFFY+4 3oG0azPvSNPLXl1d2FTfy0zC2nRNzfYdMBdfX/7+5/rpfeSwCQfWqoQ+zbvfiWHbA8 a1VQXWYR7iLj7KpmMqOy5j0HxAa6841d/+J1EqPkgyePGGd6/Lbias2aaqFYVk92xZ K8dBSkuie0qYQ== Message-ID: Date: Thu, 25 Dec 2025 10:32:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/3] mm: pagewalk: simplify hugepage boundary To: Matthew Wilcox , David Laight Cc: Lance Yang , baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, akpm@linux-foundation.org, axelrasmussen@google.com, chandna.sahil@gmail.com, chengming.zhou@linux.dev, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, mhocko@suse.com, nphamcs@gmail.com, rppt@kernel.org, shakeel.butt@linux.dev, surenb@google.com, vbabka@suse.cz, weixugc@google.com, yosry.ahmed@linux.dev, yuanchu@google.com, zhengqi.arch@bytedance.com, Lance Yang References: <62a2d7ba-e7c3-4153-b227-c08802ca9e1c@linux.alibaba.com> <20251224092332.53214-1-ioworker0@gmail.com> <20251224140829.2ec7bbae@pumpkin> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: F04C31C0005 X-Stat-Signature: jfnsg95rumha9zdd3kswj3rtuso3oc85 X-Rspam-User: X-HE-Tag: 1766655176-918246 X-HE-Meta: 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 fqG1McOx xebZTLOcx6yiupDffFnlW41zacDXVjYz3veCWLsirq2VrMRbkTvEyrBN4in+s6vQAilxKaFU0l8AMh2VVvqOCXQNs9yuD3VEoYj8aQSyvV31XjzA3ZAm1TIcIQS9dVjldzRs7gcsIG85lTn/4RC/M+3AbtO+ZOXaUQexhcETyCdicchafsj9T2z7D7Rl156WsAi8CMlfxPOuO+hjmci5Utk39lfJXoXUOb7ZgXaNBnPwoTm8u8VGUcPpb9yF/HsfJwqk02nb5Ec/lLRs1NF4Th0oFVPFC/WmnfFJVEFBoabzl7mXf9SEcGVRHpCR7D4+ESPHNWC3NYFSTMQXnN+9JwKOZ7dPb5Q0FuwEWicRUoIwSaL4a0JTu0d6x6jUqG88dPHr5h2CxocgkQIN7KQneZzVc6fNHuDNu3Yg68ePe9muyELR8KfjMJrf7CA== 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 12/24/25 19:06, Matthew Wilcox wrote: > On Wed, Dec 24, 2025 at 02:08:29PM +0000, David Laight wrote: >>>>> +++ b/mm/pagewalk.c >>>>> @@ -312,8 +312,7 @@ static int walk_pgd_range(unsigned long addr, unsigned long end, >>>>> static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr, >>>>> unsigned long end) >>>>> { >>>>> - unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h); >>>>> - return boundary < end ? boundary : end; >>>>> + return min(ALIGN(addr, huge_page_size(h)), end); >>>>> } >>>> >>>> Please drop this patch from the mm-new branch, as it causes >>>> 'run_vmtests.sh' to hang. Specifically, it leads to the system hanging >>>> when executing hugepage-vmemmap test, because the program falls into an >>>> infinite loop in walk_hugetlb_range() and cannot break out. >>> >>> Good catch! The problem is that ALIGN() returns addr itself when already >>> aligned, causing the infinite loop ... >> >> Using ALIGN(addr + 1, huge_page_size(h)) would work. >> Although it could be (addr + 1) & ~huge_page_mask(h) which is probably >> the easiest to understand. >> Some of the 'helper' macros don't really make the code easier to read. >> (And that includes a lot of uses of min().) > > Or we could go back to my original suggestion. > > https://lore.kernel.org/linux-mm/aRyOWrARRlUCeEz6@casper.infradead.org/ > > which was in v2: > > https://lore.kernel.org/linux-mm/f802959f58865371ba1b10081bced98e3784c5e4.1763796152.git.chandna.sahil@gmail.com/ I'm starting to wonder whether we should just leave that code alone :) -- Cheers David