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Thu, 16 Oct 2025 08:59:39 +0800 (CST) Received: from dggpemf100008.china.huawei.com (unknown [7.185.36.138]) by mail.maildlp.com (Postfix) with ESMTPS id 48945180064; Thu, 16 Oct 2025 09:00:39 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemf100008.china.huawei.com (7.185.36.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 16 Oct 2025 09:00:38 +0800 Message-ID: <0d26ce96-2c59-47bd-a034-d7810ce6aa5f@huawei.com> Date: Thu, 16 Oct 2025 09:00:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/3] mm: mprotect: always skip dma pinned folio in prot_numa_skip() To: Lorenzo Stoakes CC: Andrew Morton , David Hildenbrand , , Zi Yan , Baolin Wang , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , , Sidhartha Kumar References: <20251015123516.2703660-1-wangkefeng.wang@huawei.com> <20251015123516.2703660-2-wangkefeng.wang@huawei.com> <47f69b78-8141-42a6-b04a-f67ba0b90ee9@lucifer.local> Content-Language: en-US From: Kefeng Wang In-Reply-To: <47f69b78-8141-42a6-b04a-f67ba0b90ee9@lucifer.local> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf100008.china.huawei.com (7.185.36.138) X-Rspamd-Server: rspam01 X-Stat-Signature: y54yazq95uqswtwakgps5xcyhokedtr3 X-Rspam-User: X-Rspamd-Queue-Id: DBB2D4000E X-HE-Tag: 1760576443-45755 X-HE-Meta: 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 uyXqBsIu 6KJ2gmaCjlxl02OhvII+qodv8mkhrNlSSEdAcUwLcjQdL0X7gxLM7fR+cLSBmA3MUlxC4wyO5oWGVhUD2hozoPaq0ocP2Z1EjgKL1fUwH/WliLD6seZWKOJCbL1aAF2dCHLRAMzAkiso7yxI/dGuenFD3eWtNbG9bhRr0Mc95hH1SGSkKZmCj7ukp9cDztlk7fjhe+NJuFVoIaH1TT2WpRd5KhWrLSGycnAoAJXqdUwVJIjhw+CwTJuZtUheyz96a3UzVSiPffhoRxLCiZv2u1MwZRS1uuASInh+s34denQ5WB50Kyma8B0dnEMdpFcWAIMRaOL/v5w5gP0PESvHgzJk6vgF6eocex54KdGfLyNYYZmxPISF5KdYRWM7V/vhE9xVONOMjhp0YU3LTwPX6Qi8brcOga5Z2kLO+q/X/hpBvqNRF4SVa3g7PRQ== 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 2025/10/15 23:32, Lorenzo Stoakes wrote: > On Wed, Oct 15, 2025 at 08:35:14PM +0800, Kefeng Wang wrote: >> If the folio(even not CoW folio) is dma pinned, it can't be >> migrated, so always skip pinned folio to avoid a waste of cycles >> when folios migration. > > NIT: 'when folios migration' -> 'when folios are migrated'. > > Maybe worth saying 'due to elevated reference count?' > Hope Andrew could help to update the changelog. >> >> Reviewed-by: Sidhartha Kumar >> Acked-by: David Hildenbrand >> Reviewed-by: Lance Yang >> Signed-off-by: Kefeng Wang > > LGTM though so: > > Reviewed-by: Lorenzo Stoakes Thanks all. > >> --- >> mm/mprotect.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/mm/mprotect.c b/mm/mprotect.c >> index 113b48985834..bb59a42809b8 100644 >> --- a/mm/mprotect.c >> +++ b/mm/mprotect.c >> @@ -136,9 +136,12 @@ static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr, >> if (folio_is_zone_device(folio) || folio_test_ksm(folio)) >> goto skip; >> >> - /* Also skip shared copy-on-write pages */ >> - if (is_cow_mapping(vma->vm_flags) && >> - (folio_maybe_dma_pinned(folio) || folio_maybe_mapped_shared(folio))) >> + /* Also skip shared copy-on-write folios */ >> + if (is_cow_mapping(vma->vm_flags) && folio_maybe_mapped_shared(folio)) >> + goto skip; >> + >> + /* Folios are pinned and can't be migrated */ >> + if (folio_maybe_dma_pinned(folio)) >> goto skip; >> >> /* >> -- >> 2.27.0 >> >> >