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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Shakeel Butt <shakeelb@google.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Yang Shi <shy828301@gmail.com>, Miaohe Lin <linmiaohe@huawei.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Michal Hocko <mhocko@suse.com>, Rik van Riel <riel@surriel.com>,
	Christoph Hellwig <hch@infradead.org>,
	Matthew Wilcox <willy@infradead.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Alexey Gladkov <legion@kernel.org>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Matthew Auld <matthew.auld@intel.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-api@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 08/16] huge tmpfs: fcntl(fd, F_HUGEPAGE) and fcntl(fd, F_NOHUGEPAGE)
Date: Wed, 4 Aug 2021 17:08:05 +0300	[thread overview]
Message-ID: <20210804140805.vpuerwaiqtcvc5or@box.shutemov.name> (raw)
In-Reply-To: <1c32c75b-095-22f0-aee3-30a44d4a4744@google.com>

On Fri, Jul 30, 2021 at 12:48:33AM -0700, Hugh Dickins wrote:
> Add support for fcntl(fd, F_HUGEPAGE) and fcntl(fd, F_NOHUGEPAGE), to
> select hugeness per file: useful to override the default hugeness of the
> shmem mount, when occasionally needing to store a hugepage file in a
> smallpage mount or vice versa.

Hm. But why is the new MFD_* needed if the fcntl() can do the same.

> These fcntls just specify whether or not to try for huge pages when
> allocating to the object later: F_HUGEPAGE does not touch small pages
> already allocated (though khugepaged may do so when the file is mapped
> afterwards), F_NOHUGEPAGE does not split huge pages already allocated.
> 
> Why fcntl?  Because it's already in use (for sealing) on memfds; and I'm
> anxious to keep this simple, just applying it to whole files: fallocate,
> madvise and posix_fadvise each involve a range, which would need a new
> kind of tree attached to the inode for proper support.

Most of fadvise() operations ignore the range. I like fadvise() because
it's less prescriptive: kernel is free to ignore it.

-- 
 Kirill A. Shutemov

  reply	other threads:[~2021-08-04 14:08 UTC|newest]

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30  7:22 [PATCH 00/16] tmpfs: HUGEPAGE and MEM_LOCK fcntls and memfds Hugh Dickins
2021-07-30  7:22 ` Hugh Dickins
2021-07-30  7:25 ` [PATCH 01/16] huge tmpfs: fix fallocate(vanilla) advance over huge pages Hugh Dickins
2021-07-30  7:25   ` Hugh Dickins
2021-07-30 21:36   ` Yang Shi
2021-07-30 21:36     ` Yang Shi
2021-08-01  3:38     ` Hugh Dickins
2021-08-01  3:38       ` Hugh Dickins
2021-08-02 20:36       ` Yang Shi
2021-08-02 20:36         ` Yang Shi
2021-07-30  7:28 ` [PATCH 02/16] huge tmpfs: fix split_huge_page() after FALLOC_FL_KEEP_SIZE Hugh Dickins
2021-07-30  7:28   ` Hugh Dickins
2021-07-30 23:48   ` Yang Shi
2021-07-30 23:48     ` Yang Shi
2021-07-30  7:30 ` [PATCH 03/16] huge tmpfs: remove shrinklist addition from shmem_setattr() Hugh Dickins
2021-07-30  7:30   ` Hugh Dickins
2021-07-30 21:50   ` Yang Shi
2021-07-30 21:50     ` Yang Shi
2021-07-30  7:36 ` [PATCH 04/16] huge tmpfs: revert shmem's use of transhuge_vma_enabled() Hugh Dickins
2021-07-30  7:36   ` Hugh Dickins
2021-07-30 21:56   ` Yang Shi
2021-07-30 21:56     ` Yang Shi
2021-08-01  4:01     ` Hugh Dickins
2021-08-01  4:01       ` Hugh Dickins
2021-08-02 20:39       ` Yang Shi
2021-08-02 20:39         ` Yang Shi
2021-07-30  7:39 ` [PATCH 05/16] huge tmpfs: move shmem_huge_enabled() upwards Hugh Dickins
2021-07-30  7:39   ` Hugh Dickins
2021-07-30 21:57   ` Yang Shi
2021-07-30 21:57     ` Yang Shi
2021-07-30  7:42 ` [PATCH 06/16] huge tmpfs: shmem_is_huge(vma, inode, index) Hugh Dickins
2021-07-30  7:42   ` Hugh Dickins
2021-07-30 23:34   ` Yang Shi
2021-07-30 23:34     ` Yang Shi
2021-08-01  5:22     ` Hugh Dickins
2021-08-01  5:22       ` Hugh Dickins
2021-08-01  5:37       ` Hugh Dickins
2021-08-01  5:37         ` Hugh Dickins
2021-08-02 21:14       ` Yang Shi
2021-08-02 21:14         ` Yang Shi
2021-08-04  8:28         ` Hugh Dickins
2021-08-04  8:28           ` Hugh Dickins
2021-08-04 19:01           ` Yang Shi
2021-08-04 19:01             ` Yang Shi
2021-08-06  5:21             ` Hugh Dickins
2021-08-06  5:21               ` Hugh Dickins
2021-08-06 17:41               ` Yang Shi
2021-08-06 17:41                 ` Yang Shi
2021-08-05 23:04         ` Yang Shi
2021-08-05 23:04           ` Yang Shi
2021-08-06  5:43           ` Hugh Dickins
2021-08-06  5:43             ` Hugh Dickins
2021-08-06 17:57             ` Yang Shi
2021-08-06 17:57               ` Yang Shi
2021-08-12 18:19               ` Yang Shi
2021-08-12 18:19                 ` Yang Shi
2021-07-30  7:45 ` [PATCH 07/16] memfd: memfd_create(name, MFD_HUGEPAGE) for shmem huge pages Hugh Dickins
2021-07-30  7:45   ` Hugh Dickins
2021-07-30 12:01   ` kernel test robot
2021-07-30 12:01     ` kernel test robot
2021-08-04 14:03   ` Kirill A. Shutemov
2021-08-06  3:33     ` Hugh Dickins
2021-08-06  3:33       ` Hugh Dickins
2021-07-30  7:48 ` [PATCH 08/16] huge tmpfs: fcntl(fd, F_HUGEPAGE) and fcntl(fd, F_NOHUGEPAGE) Hugh Dickins
2021-07-30  7:48   ` Hugh Dickins
2021-08-04 14:08   ` Kirill A. Shutemov [this message]
2021-08-06  4:34     ` Hugh Dickins
2021-08-06  4:34       ` Hugh Dickins
2021-07-30  7:51 ` [PATCH 09/16] huge tmpfs: decide stat.st_blksize by shmem_is_huge() Hugh Dickins
2021-07-30  7:51   ` Hugh Dickins
2021-07-30 23:40   ` Yang Shi
2021-07-30 23:40     ` Yang Shi
2021-07-30  7:55 ` [PATCH 10/16] tmpfs: fcntl(fd, F_MEM_LOCK) to memlock a tmpfs file Hugh Dickins
2021-07-30  7:55   ` Hugh Dickins
2021-08-03  1:38   ` Matthew Wilcox
2021-08-04  9:15     ` Hugh Dickins
2021-08-04  9:15       ` Hugh Dickins
2021-07-30  7:57 ` [PATCH 11/16] tmpfs: fcntl(fd, F_MEM_LOCKED) to test if memlocked Hugh Dickins
2021-07-30  7:57   ` Hugh Dickins
2021-07-30  8:00 ` [PATCH 12/16] tmpfs: refuse memlock when fallocated beyond i_size Hugh Dickins
2021-07-30  8:00   ` Hugh Dickins
2021-07-30  8:03 ` [PATCH 13/16] mm: bool user_shm_lock(loff_t size, struct ucounts *) Hugh Dickins
2021-07-30  8:03   ` Hugh Dickins
2021-07-30  8:06 ` [PATCH 14/16] mm: user_shm_lock(,,getuc) and user_shm_unlock(,,putuc) Hugh Dickins
2021-07-30  8:06   ` Hugh Dickins
2021-07-30  8:09 ` [PATCH 15/16] tmpfs: permit changing size of memlocked file Hugh Dickins
2021-07-30  8:09   ` Hugh Dickins
2021-07-30  8:13 ` [PATCH 16/16] memfd: memfd_create(name, MFD_MEM_LOCK) for memlocked shmem Hugh Dickins
2021-07-30  8:13   ` Hugh Dickins
2021-07-30 11:24   ` kernel test robot
2021-07-30 11:24     ` kernel test robot

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