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[2003:d8:2f16:1800:a9b4:1776:c5d9:1d9a]) by smtp.gmail.com with ESMTPSA id r8-20020adfda48000000b002be25db0b7bsm4403700wrl.10.2023.01.27.08.23.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Jan 2023 08:23:40 -0800 (PST) Message-ID: <4ad5163f-5368-0bd8-de9b-1400a7a653ed@redhat.com> Date: Fri, 27 Jan 2023 17:23:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH 1/2] mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps To: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Naoya Horiguchi , James Houghton , Peter Xu , Michal Hocko , Yang Shi , Vishal Moola , Matthew Wilcox , Muchun Song , Andrew Morton , stable@vger.kernel.org References: <20230126222721.222195-1-mike.kravetz@oracle.com> <20230126222721.222195-2-mike.kravetz@oracle.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230126222721.222195-2-mike.kravetz@oracle.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E1C6A20005 X-Stat-Signature: t4hzej4irizf4pgphrasroxyeqnyibqf X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1674836624-195120 X-HE-Meta: U2FsdGVkX198wid1RQAR1UJN3MtANHQ0yT7oswBCDT0Eelxe+P27fUPZdWo5bzl1u8M5nXiF9aoewduc1olAaq5YblsT3pWWReKgtPrq+nzLYHD1RduV7XqPh5D+ZQ+s4mxTB5BgqYBkrP5GXZ7Izqsm6x9pAm1n30YC8zn5vZdyeboNQkotrvzc0rhPN4meM1p7OWC1q69FnfxJ0KdYEpDmPLyFATSjQPw4UWXb7p654xTIsvFgN6V71mUxOKo4T9FsLpL8YjoAE0o1TTKer6jeysOWyVXX6vQHgc2290dOjk+xuq8XDJkGxrQ3yLK6Zc5kHSWCwDHn1yy/5hwBqBEn2IamhTklyHLqSPB+mcom4vZkA25lbJYejzkBsq+RrgccNHAFC+6OSD3o8sl+sE1mT+16J0qBNW2fdX+yOzRPqB4ikpq3B8y+Qm5lpI54YDTUOpu0W9mbp7aKraIIcSMPtX6KpE/d1FOJsvQn30zVeuIcWE4Wtl+wIu65BuMhOXWbMKEz5iKCSdjnBHoqRHANklv28EI1cgxzSYxEyjt4+l5tOwV6dWm1J+XKr6u+DkRraJKQ/7DUf4iVo3FZoMzBtTQk2unciZcANbjn9/cBcfZ1lDAGRo4f3l33smpEvkikkls/A7VPXAiR4JoiiUeuX6r3YX+igdqOh9PH8hfqsjkie6TmqYBdIBNuMQJMJMev+LYt4ShMMwyJ7GLfAcX99EQW/YemrYLZNIljJg7YG57zBxfpk+XkkewFCZI6ZV0Wl+7ve9J1qZINg0dDr0IzJxkKANUcf2yOKmmIbFxSY+jUa5RMHtAClvkSD2UAD9R3JIHeaxXmNoCmLw/o67gCMs7+bOemKFwV0mZAXIoWCQfXKTWrgOgQWMAHYXTNJ592NwElYRngJld+YjchV3AAlFzv3U2Lpi9Wz7k2XqL88BswU48GivsvF2h5i/H+n8Be0J6NNYrZBNm9DiR eaNQCKzf 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 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: On 26.01.23 23:27, Mike Kravetz wrote: > A hugetlb page will have a mapcount of 1 if mapped by multiple processes > via a shared PMD. This is because only the first process increases the > map count, and subsequent processes just add the shared PMD page to > their page table. > > page_mapcount is being used to decide if a hugetlb page is shared or > private in /proc/PID/smaps. Pages referenced via a shared PMD were > incorrectly being counted as private. > > To fix, check for a shared PMD if mapcount is 1. If a shared PMD is > found count the hugetlb page as shared. A new helper to check for a > shared PMD is added. > > Fixes: 25ee01a2fca0 ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps") > Cc: stable@vger.kernel.org > Signed-off-by: Mike Kravetz > --- > fs/proc/task_mmu.c | 10 ++++++++-- > include/linux/hugetlb.h | 12 ++++++++++++ > 2 files changed, 20 insertions(+), 2 deletions(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index e35a0398db63..cb9539879402 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -749,8 +749,14 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, > > if (mapcount >= 2) > mss->shared_hugetlb += huge_page_size(hstate_vma(vma)); > - else > - mss->private_hugetlb += huge_page_size(hstate_vma(vma)); > + else { Better: if (mapcount >= 2 || hugetlb_pmd_shared(pte)) mss->shared_hugetlb += huge_page_size(hstate_vma(vma)); else mss->private_hugetlb += huge_page_size(hstate_vma(vma)); -- Thanks, David / dhildenb