shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-07 19:30:30 +09:00
Code Issues Packages Projects Releases Wiki Activity

shmem: shmem_charge: verify max_block is not exceeded before inode update

Browse Source 
commit b1cc94ab2f upstream.

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Mike Rapoport
2017-09-06 16:22:56 -07:00
committed by Chris
parent fc504d5be2
commit af13af079b
1 changed files with 12 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
mm/shmem.c
View File

@@ -254,6 +254,14 @@ 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;
@@ -261,20 +269,11 @@ 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)