The patch titled
Subject: shmem: shmem_charge: verify max_block is not exceeded before inode update
has been added to the -mm tree. Its filename is
shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff -puN mm/shmem.c~shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update mm/shmem.c
--- a/mm/shmem.c~shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update
+++ a/mm/shmem.c
@@ -266,6 +266,14 @@ bool shmem_charge(struct inode *inode, l
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, l
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)
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxxxxxxx are
userfaultfd-non-cooperative-notify-about-unmap-of-destination-during-mremap.patch
userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update.patch
shmem-introduce-shmem_inode_acct_block.patch
userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support.patch
userfaultfd-mcopy_atomic-introduce-mfill_atomic_pte-helper.patch
userfaultfd-shmem-wire-up-shmem_mfill_zeropage_pte.patch
userfaultfd-report-uffdio_zeropage-as-available-for-shmem-vmas.patch
userfaultfd-selftest-enable-testing-of-uffdio_zeropage-for-shmem.patch
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