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Mon, 7 Apr 2025 15:26:06 +0800 Message-ID: <0a664ec5-f575-d0d2-dbb9-c6d75bfcc626@huawei.com> Date: Mon, 7 Apr 2025 15:26:05 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v2] mm/hugetlb: fix set_max_huge_pages() when there are surplus pages To: Oscar Salvador CC: , , , , References: <20250401082339.676723-1-tujinjiang@huawei.com> From: Jinjiang Tu In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.13] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemo200002.china.huawei.com (7.202.195.209) X-Stat-Signature: mh1askf8z5mje85am8gds1j635wcuwz6 X-Rspam-User: X-Rspamd-Queue-Id: 2029C2000A X-Rspamd-Server: rspam08 X-HE-Tag: 1744010770-853277 X-HE-Meta: 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 uwlJWiHw rLd5EpDI+wJEhnHp9GJkMcTF+I8TNQJYGQpTbYge3++WcTDh13hJUiFEitgHv9xdj0pJSyGzF3JOE9IIaDknRHDhWGPHGO0K/Vrhlb3lZo6av7tDP4fIJXSxcNn+vRprpwm8UeIs5i6Nvc6M43uLtjfZU4GDJFpKYliF/GdS1El7OWxyHG+qKPs7Ata4rqKTBeLQ4PhfmgtcZEVk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 在 2025/4/6 18:37, Oscar Salvador 写道: > On Sun, Apr 06, 2025 at 12:30:43PM +0200, Oscar Salvador wrote: >> On Fri, Apr 04, 2025 at 03:18:09PM +0200, Oscar Salvador wrote: >>> @@ -3960,7 +3961,12 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, >>> * and won't grow the pool anywhere else. Not until one of the >>> * sysctls are changed, or the surplus pages go out of use. >>> */ >>> - min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; >>> + if (h->free_huge_pages > persistent_huge_pages(h)) >>> + substract = h->free_huge_pages - h->surplus_huge_pages; >>> + else >>> + h->free_huge_pages; >> Ofc, this wanted to be substract = h->free_huge_pages. > Although I am thinking that instead of playing smart, we really need a counter > to tell us how many _free_ surplus pages due to hvo failing to recompose back > those pages we have at any given time, then the substracting thing becomes > easier. free surplus count seem to only be used in set_max_huge_pages(), which is called rarely. Since it can be calcuated, it isn't necessary to maintain a extra count. Thanks. > >