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From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>,
	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: [PATCH 16/16] memfd: memfd_create(name, MFD_MEM_LOCK) for memlocked shmem
Date: Fri, 30 Jul 2021 01:13:00 -0700 (PDT)	[thread overview]
Message-ID: <be7c30cc-20fd-b5d6-83a2-366410753145@google.com> (raw)
In-Reply-To: <2862852d-badd-7486-3a8e-c5ea9666d6fb@google.com>

Now that the size of a memlocked file can be changed, memfd_create() can
accept an MFD_MEM_LOCK flag to request memlocking, even though the initial
size is of course 0.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
 include/uapi/linux/memfd.h |  1 +
 mm/memfd.c                 |  7 +++++--
 mm/shmem.c                 | 13 ++++++++++++-
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
index 8358a69e78cc..9113b5aa1763 100644
--- a/include/uapi/linux/memfd.h
+++ b/include/uapi/linux/memfd.h
@@ -9,6 +9,7 @@
 #define MFD_ALLOW_SEALING	0x0002U
 #define MFD_HUGETLB		0x0004U		/* Use hugetlbfs */
 #define MFD_HUGEPAGE		0x0008U		/* Use huge tmpfs */
+#define MFD_MEM_LOCK		0x0010U		/* Memlock tmpfs */
 
 /*
  * Huge page size encoding when MFD_HUGETLB is specified, and a huge page
diff --git a/mm/memfd.c b/mm/memfd.c
index 0d1a504d2fc9..e39f9eed55d2 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -248,7 +248,8 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
 #define MFD_ALL_FLAGS  (MFD_CLOEXEC | \
 			MFD_ALLOW_SEALING | \
 			MFD_HUGETLB | \
-			MFD_HUGEPAGE)
+			MFD_HUGEPAGE | \
+			MFD_MEM_LOCK)
 
 SYSCALL_DEFINE2(memfd_create,
 		const char __user *, uname,
@@ -262,7 +263,7 @@ SYSCALL_DEFINE2(memfd_create,
 
 	if (flags & MFD_HUGETLB) {
 		/* Disallow huge tmpfs when choosing hugetlbfs */
-		if (flags & MFD_HUGEPAGE)
+		if (flags & (MFD_HUGEPAGE | MFD_MEM_LOCK))
 			return -EINVAL;
 		/* Allow huge page size encoding in flags. */
 		if (flags & ~(unsigned int)(MFD_ALL_FLAGS |
@@ -314,6 +315,8 @@ SYSCALL_DEFINE2(memfd_create,
 
 		if (flags & MFD_HUGEPAGE)
 			vm_flags |= VM_HUGEPAGE;
+		if (flags & MFD_MEM_LOCK)
+			vm_flags |= VM_LOCKED;
 		file = shmem_file_setup(name, 0, vm_flags);
 	}
 
diff --git a/mm/shmem.c b/mm/shmem.c
index fa4a264453bf..a0a83e59ae07 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2395,7 +2395,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		spin_lock_init(&info->lock);
 		atomic_set(&info->stop_eviction, 0);
 		info->seals = F_SEAL_SEAL;
-		info->flags = flags & VM_NORESERVE;
+		info->flags = flags & (VM_NORESERVE | VM_LOCKED);
 		if ((flags & VM_HUGEPAGE) &&
 		    transparent_hugepage_allowed(sbinfo) &&
 		    !test_bit(MMF_DISABLE_THP, &current->mm->flags))
@@ -4254,6 +4254,17 @@ static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, l
 	inode->i_size = size;
 	clear_nlink(inode);	/* It is unlinked */
 	res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
+	if (!IS_ERR(res) && (flags & VM_LOCKED)) {
+		struct ucounts *ucounts = current_ucounts();
+		/*
+		 * Only memfd_create() may pass VM_LOCKED, and it passes
+		 * size 0; but avoid that assumption in case it changes.
+		 */
+		if (user_shm_lock(size, ucounts, true))
+			SHMEM_I(inode)->mlock_ucounts = ucounts;
+		else
+			res = ERR_PTR(-EPERM);
+	}
 	if (!IS_ERR(res))
 		res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
 				&shmem_file_operations);
-- 
2.26.2


      parent reply	other threads:[~2021-07-30  8:13 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
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 ` Hugh Dickins [this message]

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