From: Hugh Dickins <hughd@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>,
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>,
"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 10/16] tmpfs: fcntl(fd, F_MEM_LOCK) to memlock a tmpfs file
Date: Wed, 4 Aug 2021 02:15:26 -0700 (PDT) [thread overview]
Message-ID: <7077b94a-d894-4d97-4b3e-23f516d58591@google.com> (raw)
In-Reply-To: <YQieHio1oUKCfgqq@casper.infradead.org>
On Tue, 3 Aug 2021, Matthew Wilcox wrote:
> On Fri, Jul 30, 2021 at 12:55:22AM -0700, Hugh Dickins wrote:
> > A new uapi to lock the files on tmpfs in memory, to protect against swap
> > without mapping the files. This commit introduces two new commands to
> > fcntl and shmem: F_MEM_LOCK and F_MEM_UNLOCK. The locking will be
> > charged against RLIMIT_MEMLOCK of uid in namespace of the caller.
>
> It's not clear to me why this is limited to shmfs. Would it not also
> make sense for traditional filesystems, eg to force chrome's text pages
> to stay in the page cache, no matter how much memory the tabs allocate?
Right: if VFS people would like this to be available for all filesystems,
that's fine by me - it's just that we have not given thought to other
filesystems, and the demand was for tmpfs, so that was where to start.
I'm more confident adding fields to shmem inode than to generic inode.
(Plus tmpfs does have a stronger claim on CAP_IPC_LOCK etc, but there's
no real reason why that cannot be extended to similar use by other FSs).
hugetlbfs and ramfs, where the files are already memlocked? Not worth a
special case, I think: if someone uses up memlock quota on them, so be it.
It looks as if tmpfs would still want its own special case, just to
handle the FALLOC_FL_KEEP_SIZE issue (see 12/16): tmpfs has beyond-i_size
pages in memory, but accounts them evictable; whereas I doubt any storage
filesystems would be using memory for them.
To be clear: I'm not intending to extend this to other filesystems at
the moment; but happy to do so if that's the consensus.
Hugh
next prev parent reply other threads:[~2021-08-04 9:15 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
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 [this message]
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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