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authorMike Rapoport <rppt@linux.vnet.ibm.com>2017-09-06 16:22:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-06 17:27:28 -0700
commitb1cc94ab2f2ba31fcb2c59df0b9cf03f6d720553 (patch)
tree3894b1c311654938ea6525af4eb975c695e1966b /mm
parentfe490cc0fe9e6ee48cc48bb5dc463bc5f0f1428f (diff)
downloadop-kernel-dev-b1cc94ab2f2ba31fcb2c59df0b9cf03f6d720553.zip
op-kernel-dev-b1cc94ab2f2ba31fcb2c59df0b9cf03f6d720553.tar.gz
shmem: shmem_charge: verify max_block is not exceeded before inode update
Patch series "userfaultfd: enable zeropage support for shmem". These patches enable support for UFFDIO_ZEROPAGE for shared memory. The first two patches are not strictly related to userfaultfd, they are just minor refactoring to reduce amount of code duplication. This patch (of 7): Currently we update inode and shmem_inode_info before verifying that used_blocks will not exceed max_blocks. In case it will, we undo the update. Let's switch the order and move the verification of the blocks count before the inode and shmem_inode_info update. Link: http://lkml.kernel.org/r/1497939652-16528-2-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Pavel Emelyanov <xemul@virtuozzo.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.c25
1 files changed, 12 insertions, 13 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index fbcb3c9..35b5240 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -266,6 +266,14 @@ bool shmem_charge(struct inode *inode, long pages)
if (shmem_acct_block(info->flags, pages))
return false;
+
+ if (sbinfo->max_blocks) {
+ if (percpu_counter_compare(&sbinfo->used_blocks,
+ sbinfo->max_blocks - pages) > 0)
+ goto unacct;
+ percpu_counter_add(&sbinfo->used_blocks, pages);
+ }
+
spin_lock_irqsave(&info->lock, flags);
info->alloced += pages;
inode->i_blocks += pages * BLOCKS_PER_PAGE;
@@ -273,20 +281,11 @@ bool shmem_charge(struct inode *inode, long pages)
spin_unlock_irqrestore(&info->lock, flags);
inode->i_mapping->nrpages += pages;
- if (!sbinfo->max_blocks)
- return true;
- if (percpu_counter_compare(&sbinfo->used_blocks,
- sbinfo->max_blocks - pages) > 0) {
- inode->i_mapping->nrpages -= pages;
- spin_lock_irqsave(&info->lock, flags);
- info->alloced -= pages;
- shmem_recalc_inode(inode);
- spin_unlock_irqrestore(&info->lock, flags);
- shmem_unacct_blocks(info->flags, pages);
- return false;
- }
- percpu_counter_add(&sbinfo->used_blocks, pages);
return true;
+
+unacct:
+ shmem_unacct_blocks(info->flags, pages);
+ return false;
}
void shmem_uncharge(struct inode *inode, long pages)
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