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| author | Konstantin Khlebnikov <koct9i@gmail.com> | 2014-08-06 16:06:34 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-06 18:01:19 -0700 |
| commit | 77142517990fd3d982678c2945ea2c4188ec5f9a (patch) | |
| tree | 9ad927b6f48ad2e6a89830ae4f3ee3fa99976646 | |
| parent | 66ee4b8887ec5ce04bae3e840d206db7b7ad34d1 (diff) | |
| download | linux-77142517990fd3d982678c2945ea2c4188ec5f9a.tar.gz linux-77142517990fd3d982678c2945ea2c4188ec5f9a.tar.bz2 linux-77142517990fd3d982678c2945ea2c4188ec5f9a.zip | |
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>
| -rw-r--r-- | mm/shmem.c | 17 |
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; } |