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authorKonstantin Khlebnikov <koct9i@gmail.com>2014-08-06 16:06:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-06 18:01:19 -0700
commit77142517990fd3d982678c2945ea2c4188ec5f9a (patch)
tree9ad927b6f48ad2e6a89830ae4f3ee3fa99976646 /mm
parent66ee4b8887ec5ce04bae3e840d206db7b7ad34d1 (diff)
downloadlinux-77142517990fd3d982678c2945ea2c4188ec5f9a.tar.gz
shmem: update memory reservation on truncate
A shared anonymous mapping created without MAP_NORESERVE holds memory reservation for whole range of shmem segment. Usually there is no way to change its size, but /proc/<pid>/map_files/... (available if CONFIG_CHECKPOINT_RESTORE=y) allows that. This patch adjusts the memory reservation in shmem_setattr(). Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/shmem.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 3609d31ad0dd..57fd82a5af7a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -149,6 +149,19 @@ static inline void shmem_unacct_size(unsigned long flags, loff_t size)
vm_unacct_memory(VM_ACCT(size));
}
+static inline int shmem_reacct_size(unsigned long flags,
+ loff_t oldsize, loff_t newsize)
+{
+ if (!(flags & VM_NORESERVE)) {
+ if (VM_ACCT(newsize) > VM_ACCT(oldsize))
+ return security_vm_enough_memory_mm(current->mm,
+ VM_ACCT(newsize) - VM_ACCT(oldsize));
+ else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
+ vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
+ }
+ return 0;
+}
+
/*
* ... whereas tmpfs objects are accounted incrementally as
* pages are allocated, in order to allow huge sparse files.
@@ -549,6 +562,10 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
loff_t newsize = attr->ia_size;
if (newsize != oldsize) {
+ error = shmem_reacct_size(SHMEM_I(inode)->flags,
+ oldsize, newsize);
+ if (error)
+ return error;
i_size_write(inode, newsize);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
}