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
next prev parent reply other threads:[~2021-08-04 14:08 UTC|newest] Thread overview: 45+ 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 7:25 ` [PATCH 01/16] huge tmpfs: fix fallocate(vanilla) advance over huge pages Hugh Dickins 2021-07-30 21:36 ` Yang Shi 2021-08-01 3:38 ` Hugh Dickins 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 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 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 21:56 ` Yang Shi 2021-08-01 4:01 ` Hugh Dickins 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 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 23:34 ` Yang Shi 2021-08-01 5:22 ` Hugh Dickins 2021-08-01 5:37 ` Hugh Dickins 2021-08-02 21:14 ` Yang Shi 2021-08-04 8:28 ` Hugh Dickins 2021-08-04 19:01 ` Yang Shi 2021-08-06 5:21 ` Hugh Dickins 2021-08-06 17:41 ` Yang Shi 2021-08-05 23:04 ` Yang Shi 2021-08-06 5:43 ` Hugh Dickins 2021-08-06 17:57 ` 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 2021-08-04 14:03 ` Kirill A. Shutemov 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 2021-08-04 14:08 ` Kirill A. Shutemov [this message] 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 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 2021-08-03 1:38 ` Matthew Wilcox 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 8:00 ` [PATCH 12/16] tmpfs: refuse memlock when fallocated beyond i_size 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 8:06 ` [PATCH 14/16] mm: user_shm_lock(,,getuc) and user_shm_unlock(,,putuc) Hugh Dickins 2021-07-30 8:09 ` [PATCH 15/16] tmpfs: permit changing size of memlocked file Hugh Dickins 2021-07-30 8:13 ` [PATCH 16/16] memfd: memfd_create(name, MFD_MEM_LOCK) for memlocked shmem Hugh Dickins
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