From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v1 3/6] fs/proc/task_mmu: properly detect PM_MMAP_EXCLUSIVE per page of PMD-mapped THPs
Date: Mon, 10 Jun 2024 06:51:09 +0200 [thread overview]
Message-ID: <ZmaGPfSsJ1tguUry@localhost.localdomain> (raw)
In-Reply-To: <20240607122357.115423-4-david@redhat.com>
On Fri, Jun 07, 2024 at 02:23:54PM +0200, David Hildenbrand wrote:
> We added PM_MMAP_EXCLUSIVE in 2015 via commit 77bb499bb60f ("pagemap: add
> mmap-exclusive bit for marking pages mapped only here"), when THPs could
> not be partially mapped and page_mapcount() returned something
> that was true for all pages of the THP.
>
> In 2016, we added support for partially mapping THPs via
> commit 53f9263baba6 ("mm: rework mapcount accounting to enable 4k mapping
> of THPs") but missed to determine PM_MMAP_EXCLUSIVE as well per page.
>
> Checking page_mapcount() on the head page does not tell the whole story.
>
> We should check each individual page. In a future without per-page
> mapcounts it will be different, but we'll change that to be consistent
> with PTE-mapped THPs once we deal with that.
>
> Fixes: 53f9263baba6 ("mm: rework mapcount accounting to enable 4k mapping of THPs")
> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
--
Oscar Salvador
SUSE Labs
next prev parent reply other threads:[~2024-06-10 4:51 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-07 12:23 [PATCH v1 0/6] fs/proc: move page_mapcount() to fs/proc/internal.h David Hildenbrand
2024-06-07 12:23 ` [PATCH v1 1/6] fs/proc/task_mmu: indicate PM_FILE for PMD-mapped file THP David Hildenbrand
2024-06-07 13:21 ` Kirill A . Shutemov
2024-06-07 13:36 ` Lance Yang
2024-06-10 4:32 ` Oscar Salvador
2024-06-07 12:23 ` [PATCH v1 2/6] fs/proc/task_mmu: don't indicate PM_MMAP_EXCLUSIVE without PM_PRESENT David Hildenbrand
2024-06-10 4:38 ` Oscar Salvador
2024-06-11 7:13 ` Oscar Salvador
2024-06-11 10:51 ` David Hildenbrand
2024-06-11 10:45 ` David Hildenbrand
2024-06-10 4:49 ` Oscar Salvador
2024-06-11 10:50 ` David Hildenbrand
2024-06-11 11:15 ` Oscar Salvador
2024-06-07 12:23 ` [PATCH v1 3/6] fs/proc/task_mmu: properly detect PM_MMAP_EXCLUSIVE per page of PMD-mapped THPs David Hildenbrand
2024-06-10 4:51 ` Oscar Salvador [this message]
2024-06-07 12:23 ` [PATCH v1 4/6] fs/proc/task_mmu: account non-present entries as "maybe shared, but no idea how often" David Hildenbrand
2024-06-07 12:23 ` [PATCH v1 5/6] fs/proc: move page_mapcount() to fs/proc/internal.h David Hildenbrand
2024-06-07 12:23 ` [PATCH v1 6/6] Documentation/admin-guide/mm/pagemap.rst: drop "Using pagemap to do something useful" David Hildenbrand
2024-06-07 13:18 ` [PATCH v1 0/6] fs/proc: move page_mapcount() to fs/proc/internal.h Oscar Salvador
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