4.9-stable review patch. If anyone has any objections, please let me know.
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commit b1cc94ab2f2ba31fcb2c59df0b9cf03f6d720553 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.i... 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 --- mm/shmem.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c index 358a92be43eb..b26f11221ea8 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -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)