Re: [PATCH 2/2] hugepages: Fix use after free bug in "quota" handling

From: Hillf Danton
Date: Wed Mar 07 2012 - 07:28:40 EST

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On Wed, Mar 7, 2012 at 12:48 PM, David Gibson
<david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> hugetlbfs_{get,put}_quota() are badly named. ÂThey don't interact with the
> general quota handling code, and they don't much resemble its behaviour.
> Rather than being about maintaining limits on on-disk block usage by
> particular users, they are instead about maintaining limits on in-memory
> page usage (including anonymous MAP_PRIVATE copied-on-write pages)
> associated with a particular hugetlbfs filesystem instance.
>
> Worse, they work by having callbacks to the hugetlbfs filesystem code from
> the low-level page handling code, in particular from free_huge_page().
> This is a layering violation of itself, but more importantly, if the kernel
> does a get_user_pages() on hugepages (which can happen from KVM amongst
> others), then the free_huge_page() can be delayed until after the
> associated inode has already been freed. ÂIf an unmount occurs at the
> wrong time, even the hugetlbfs superblock where the "quota" limits are
> stored may have been freed.
>
> Andrew Barry proposed a patch to fix this by having hugepages, instead of
> storing a pointer to their address_space and reaching the superblock from
> there, had the hugepages store pointers directly to the superblock, bumping
> the reference count as appropriate to avoid it being freed. ÂAndrew Morton
> rejected that version, however, on the grounds that it made the existing
> layering violation worse.
>
> This is a reworked version of Andrew's patch, which removes the extra, and
> some of the existing, layering violation. ÂIt works by introducing the
> concept of a hugepage "subpool" at the lower hugepage mm layer - that is
> a finite logical pool of hugepages to allocate from. Âhugetlbfs now creates
> a subpool for each filesystem instance with a page limit set, and a pointer
> to the subpool gets added to each allocated hugepage, instead of the
> address_space pointer used now. ÂThe subpool has its own lifetime and is
> only freed once all pages in it _and_ all other references to it (i.e.
> superblocks) are gone.
>
> subpools are optional - a NULL subpool pointer is taken by the code to mean
> that no subpool limits are in effect.
>
> Previous discussion of this bug found in: Â"Fix refcounting in hugetlbfs
> quota handling.". See: Âhttps://lkml.org/lkml/2011/8/11/28 or
> http://marc.info/?l=linux-mm&m=126928970510627&w=1
>
> v2: Fixed a bug spotted by Hillf Danton, and removed the extra parameter to
> alloc_huge_page() - since it already takes the vma, it is not necessary.
>
> Signed-off-by: Andrew Barry <abarry@xxxxxxxx>
> Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Hillf Danton <dhillf@xxxxxxxxx>
> ---
> Âfs/hugetlbfs/inode.c Â Â| Â 54 +++++++-----------
> Âinclude/linux/hugetlb.h | Â 14 ++++--
> Âmm/hugetlb.c Â Â Â Â Â Â| Â135 +++++++++++++++++++++++++++++++++++++---------
> Â3 files changed, 139 insertions(+), 64 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index bb0e366..74c6ba2 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -626,9 +626,15 @@ static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
> Â Â Â Â Â Â Â Âspin_lock(&sbinfo->stat_lock);
> Â Â Â Â Â Â Â Â/* If no limits set, just report 0 for max/free/used
> Â Â Â Â Â Â Â Â * blocks, like simple_statfs() */
> - Â Â Â Â Â Â Â if (sbinfo->max_blocks >= 0) {
> - Â Â Â Â Â Â Â Â Â Â Â buf->f_blocks = sbinfo->max_blocks;
> - Â Â Â Â Â Â Â Â Â Â Â buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
> + Â Â Â Â Â Â Â if (sbinfo->spool) {
> + Â Â Â Â Â Â Â Â Â Â Â long free_pages;
> +
> + Â Â Â Â Â Â Â Â Â Â Â spin_lock(&sbinfo->spool->lock);
> + Â Â Â Â Â Â Â Â Â Â Â buf->f_blocks = sbinfo->spool->max_hpages;
> + Â Â Â Â Â Â Â Â Â Â Â free_pages = sbinfo->spool->max_hpages
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â - sbinfo->spool->used_hpages;
> + Â Â Â Â Â Â Â Â Â Â Â buf->f_bavail = buf->f_bfree = free_pages;
> + Â Â Â Â Â Â Â Â Â Â Â spin_unlock(&sbinfo->spool->lock);
> Â Â Â Â Â Â Â Â Â Â Â Âbuf->f_files = sbinfo->max_inodes;
> Â Â Â Â Â Â Â Â Â Â Â Âbuf->f_ffree = sbinfo->free_inodes;
> Â Â Â Â Â Â Â Â}
> @@ -644,6 +650,10 @@ static void hugetlbfs_put_super(struct super_block *sb)
>
> Â Â Â Âif (sbi) {
> Â Â Â Â Â Â Â Âsb->s_fs_info = NULL;
> +
> + Â Â Â Â Â Â Â if (sbi->spool)
> + Â Â Â Â Â Â Â Â Â Â Â hugepage_put_subpool(sbi->spool);
> +
> Â Â Â Â Â Â Â Âkfree(sbi);
> Â Â Â Â}
> Â}
> @@ -874,10 +884,14 @@ hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
> Â Â Â Âsb->s_fs_info = sbinfo;
> Â Â Â Âsbinfo->hstate = config.hstate;
> Â Â Â Âspin_lock_init(&sbinfo->stat_lock);
> - Â Â Â sbinfo->max_blocks = config.nr_blocks;
> - Â Â Â sbinfo->free_blocks = config.nr_blocks;
> Â Â Â Âsbinfo->max_inodes = config.nr_inodes;
> Â Â Â Âsbinfo->free_inodes = config.nr_inodes;
> + Â Â Â sbinfo->spool = NULL;
> + Â Â Â if (config.nr_blocks != -1) {
> + Â Â Â Â Â Â Â sbinfo->spool = hugepage_new_subpool(config.nr_blocks);
> + Â Â Â Â Â Â Â if (!sbinfo->spool)
> + Â Â Â Â Â Â Â Â Â Â Â goto out_free;
> + Â Â Â }
> Â Â Â Âsb->s_maxbytes = MAX_LFS_FILESIZE;
> Â Â Â Âsb->s_blocksize = huge_page_size(config.hstate);
> Â Â Â Âsb->s_blocksize_bits = huge_page_shift(config.hstate);
> @@ -896,38 +910,12 @@ hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
> Â Â Â Âsb->s_root = root;
> Â Â Â Âreturn 0;
> Âout_free:
> + Â Â Â if (sbinfo->spool)
> + Â Â Â Â Â Â Â kfree(sbinfo->spool);
> Â Â Â Âkfree(sbinfo);
> Â Â Â Âreturn -ENOMEM;
> Â}
>
> -int hugetlb_get_quota(struct address_space *mapping, long delta)
> -{
> - Â Â Â int ret = 0;
> - Â Â Â struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
> -
> - Â Â Â if (sbinfo->free_blocks > -1) {
> - Â Â Â Â Â Â Â spin_lock(&sbinfo->stat_lock);
> - Â Â Â Â Â Â Â if (sbinfo->free_blocks - delta >= 0)
> - Â Â Â Â Â Â Â Â Â Â Â sbinfo->free_blocks -= delta;
> - Â Â Â Â Â Â Â else
> - Â Â Â Â Â Â Â Â Â Â Â ret = -ENOMEM;
> - Â Â Â Â Â Â Â spin_unlock(&sbinfo->stat_lock);
> - Â Â Â }
> -
> - Â Â Â return ret;
> -}
> -
> -void hugetlb_put_quota(struct address_space *mapping, long delta)
> -{
> - Â Â Â struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
> -
> - Â Â Â if (sbinfo->free_blocks > -1) {
> - Â Â Â Â Â Â Â spin_lock(&sbinfo->stat_lock);
> - Â Â Â Â Â Â Â sbinfo->free_blocks += delta;
> - Â Â Â Â Â Â Â spin_unlock(&sbinfo->stat_lock);
> - Â Â Â }
> -}
> -
> Âstatic struct dentry *hugetlbfs_mount(struct file_system_type *fs_type,
> Â Â Â Âint flags, const char *dev_name, void *data)
> Â{
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 7adc492..cf01817 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -14,6 +14,15 @@ struct user_struct;
> Â#include <linux/shm.h>
> Â#include <asm/tlbflush.h>
>
> +struct hugepage_subpool {
> + Â Â Â spinlock_t lock;
> + Â Â Â long count;
> + Â Â Â long max_hpages, used_hpages;
> +};
> +
> +struct hugepage_subpool *hugepage_new_subpool(long nr_blocks);
> +void hugepage_put_subpool(struct hugepage_subpool *spool);
> +
> Âint PageHuge(struct page *page);
>
> Âvoid reset_vma_resv_huge_pages(struct vm_area_struct *vma);
> @@ -129,12 +138,11 @@ enum {
>
> Â#ifdef CONFIG_HUGETLBFS
> Âstruct hugetlbfs_sb_info {
> - Â Â Â long Â Âmax_blocks; Â /* blocks allowed */
> - Â Â Â long Â Âfree_blocks; Â/* blocks free */
> Â Â Â Âlong Â Âmax_inodes; Â /* inodes allowed */
> Â Â Â Âlong Â Âfree_inodes; Â/* inodes free */
> Â Â Â Âspinlock_t Â Â Âstat_lock;
> Â Â Â Âstruct hstate *hstate;
> + Â Â Â struct hugepage_subpool *spool;
> Â};
>
> Âstatic inline struct hugetlbfs_sb_info *HUGETLBFS_SB(struct super_block *sb)
> @@ -146,8 +154,6 @@ extern const struct file_operations hugetlbfs_file_operations;
> Âextern const struct vm_operations_struct hugetlb_vm_ops;
> Âstruct file *hugetlb_file_setup(const char *name, size_t size, vm_flags_t acct,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âstruct user_struct **user, int creat_flags);
> -int hugetlb_get_quota(struct address_space *mapping, long delta);
> -void hugetlb_put_quota(struct address_space *mapping, long delta);
>
> Âstatic inline int is_file_hugepages(struct file *file)
> Â{
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 5f34bd8..36b38b3a 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -53,6 +53,84 @@ static unsigned long __initdata default_hstate_size;
> Â*/
> Âstatic DEFINE_SPINLOCK(hugetlb_lock);
>
> +static inline void unlock_or_release_subpool(struct hugepage_subpool *spool)
> +{
> + Â Â Â bool free = (spool->count == 0) && (spool->used_hpages == 0);
> +
> + Â Â Â spin_unlock(&spool->lock);
> +
> + Â Â Â /* If no pages are used, and no other handles to the subpool
> + Â Â Â Â* remain, free the subpool the subpool remain */
> + Â Â Â if (free)
> + Â Â Â Â Â Â Â kfree(spool);
> +}
> +
> +struct hugepage_subpool *hugepage_new_subpool(long nr_blocks)
> +{
> + Â Â Â struct hugepage_subpool *spool;
> +
> + Â Â Â spool = kmalloc(sizeof(*spool), GFP_KERNEL);
> + Â Â Â if (!spool)
> + Â Â Â Â Â Â Â return NULL;
> +
> + Â Â Â spin_lock_init(&spool->lock);
> + Â Â Â spool->count = 1;
> + Â Â Â spool->max_hpages = nr_blocks;
> + Â Â Â spool->used_hpages = 0;
> +
> + Â Â Â return spool;
> +}
> +
> +void hugepage_put_subpool(struct hugepage_subpool *spool)
> +{
> + Â Â Â spin_lock(&spool->lock);
> + Â Â Â BUG_ON(!spool->count);
> + Â Â Â spool->count--;
> + Â Â Â unlock_or_release_subpool(spool);
> +}
> +
> +static int hugepage_subpool_get_pages(struct hugepage_subpool *spool,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â long delta)
> +{
> + Â Â Â int ret = 0;
> +
> + Â Â Â if (!spool)
> + Â Â Â Â Â Â Â return 0;
> +
> + Â Â Â spin_lock(&spool->lock);
> + Â Â Â if ((spool->used_hpages + delta) <= spool->max_hpages) {
> + Â Â Â Â Â Â Â spool->used_hpages += delta;
> + Â Â Â } else {
> + Â Â Â Â Â Â Â ret = -ENOMEM;
> + Â Â Â }
> + Â Â Â spin_unlock(&spool->lock);
> +
> + Â Â Â return ret;
> +}
> +
> +static void hugepage_subpool_put_pages(struct hugepage_subpool *spool,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âlong delta)
> +{
> + Â Â Â if (!spool)
> + Â Â Â Â Â Â Â return;
> +
> + Â Â Â spin_lock(&spool->lock);
> + Â Â Â spool->used_hpages -= delta;
> + Â Â Â /* If hugetlbfs_put_super couldn't free spool due to
> + Â Â Â * an outstanding quota reference, free it now. */
> + Â Â Â unlock_or_release_subpool(spool);
> +}
> +
> +static inline struct hugepage_subpool *subpool_inode(struct inode *inode)
> +{
> + Â Â Â return HUGETLBFS_SB(inode->i_sb)->spool;
> +}
> +
> +static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
> +{
> + Â Â Â return subpool_inode(vma->vm_file->f_dentry->d_inode);
> +}
> +
> Â/*
> Â* Region tracking -- allows tracking of reservations and instantiated pages
> Â* Â Â Â Â Â Â Â Â Â Âacross the pages in a mapping.
> @@ -533,9 +611,9 @@ static void free_huge_page(struct page *page)
> Â Â Â Â */
> Â Â Â Âstruct hstate *h = page_hstate(page);
> Â Â Â Âint nid = page_to_nid(page);
> - Â Â Â struct address_space *mapping;
> + Â Â Â struct hugepage_subpool *spool =
> + Â Â Â Â Â Â Â (struct hugepage_subpool *)page_private(page);
>
> - Â Â Â mapping = (struct address_space *) page_private(page);
> Â Â Â Âset_page_private(page, 0);
> Â Â Â Âpage->mapping = NULL;
> Â Â Â ÂBUG_ON(page_count(page));
> @@ -551,8 +629,7 @@ static void free_huge_page(struct page *page)
> Â Â Â Â Â Â Â Âenqueue_huge_page(h, page);
> Â Â Â Â}
> Â Â Â Âspin_unlock(&hugetlb_lock);
> - Â Â Â if (mapping)
> - Â Â Â Â Â Â Â hugetlb_put_quota(mapping, 1);
> + Â Â Â hugepage_subpool_put_pages(spool, 1);

Like current code, quota is handed back *unconditionally*, but ...

> Â}
>
> Âstatic void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
> @@ -966,11 +1043,12 @@ static void return_unused_surplus_pages(struct hstate *h,
> Â/*
> Â* Determine if the huge page at addr within the vma has an associated
> Â* reservation. ÂWhere it does not we will need to logically increase
> - * reservation and actually increase quota before an allocation can occur.
> - * Where any new reservation would be required the reservation change is
> - * prepared, but not committed. ÂOnce the page has been quota'd allocated
> - * an instantiated the change should be committed via vma_commit_reservation.
> - * No action is required on failure.
> + * reservation and actually increase subpool usage before an allocation
> + * can occur. ÂWhere any new reservation would be required the
> + * reservation change is prepared, but not committed. ÂOnce the page
> + * has been allocated from the subpool and instantiated the change should
> + * be committed via vma_commit_reservation. ÂNo action is required on
> + * failure.
> Â*/
> Âstatic long vma_needs_reservation(struct hstate *h,
> Â Â Â Â Â Â Â Â Â Â Â Âstruct vm_area_struct *vma, unsigned long addr)
> @@ -1019,24 +1097,24 @@ static void vma_commit_reservation(struct hstate *h,
> Âstatic struct page *alloc_huge_page(struct vm_area_struct *vma,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Âunsigned long addr, int avoid_reserve)
> Â{
> + Â Â Â struct hugepage_subpool *spool = subpool_vma(vma);
> Â Â Â Âstruct hstate *h = hstate_vma(vma);
> Â Â Â Âstruct page *page;
> - Â Â Â struct address_space *mapping = vma->vm_file->f_mapping;
> - Â Â Â struct inode *inode = mapping->host;
> Â Â Â Âlong chg;
>
> Â Â Â Â/*
> - Â Â Â Â* Processes that did not create the mapping will have no reserves and
> - Â Â Â Â* will not have accounted against quota. Check that the quota can be
> - Â Â Â Â* made before satisfying the allocation
> - Â Â Â Â* MAP_NORESERVE mappings may also need pages and quota allocated
> - Â Â Â Â* if no reserve mapping overlaps.
> + Â Â Â Â* Processes that did not create the mapping will have no
> + Â Â Â Â* reserves and will not have accounted against subpool
> + Â Â Â Â* limit. Check that the subpool limit can be made before
> + Â Â Â Â* satisfying the allocation MAP_NORESERVE mappings may also
> + Â Â Â Â* need pages and subpool limit allocated allocated if no reserve
> + Â Â Â Â* mapping overlaps.
> Â Â Â Â */
> Â Â Â Âchg = vma_needs_reservation(h, vma, addr);
> Â Â Â Âif (chg < 0)
> Â Â Â Â Â Â Â Âreturn ERR_PTR(-VM_FAULT_OOM);
> Â Â Â Âif (chg)
> - Â Â Â Â Â Â Â if (hugetlb_get_quota(inode->i_mapping, chg))
> + Â Â Â Â Â Â Â if (hugepage_subpool_get_pages(spool, chg))
> Â Â Â Â Â Â Â Â Â Â Â Âreturn ERR_PTR(-VM_FAULT_SIGBUS);

... quota is allocated only if needed.

Given that mismatch, are you fixing the use-after-free bug, or
quota maintenance, or both?

>
> Â Â Â Âspin_lock(&hugetlb_lock);
> @@ -1046,12 +1124,12 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
> Â Â Â Âif (!page) {
> Â Â Â Â Â Â Â Âpage = alloc_buddy_huge_page(h, NUMA_NO_NODE);
> Â Â Â Â Â Â Â Âif (!page) {
> - Â Â Â Â Â Â Â Â Â Â Â hugetlb_put_quota(inode->i_mapping, chg);
> + Â Â Â Â Â Â Â Â Â Â Â hugepage_subpool_put_pages(spool, chg);
> Â Â Â Â Â Â Â Â Â Â Â Âreturn ERR_PTR(-VM_FAULT_SIGBUS);
> Â Â Â Â Â Â Â Â}
> Â Â Â Â}
>
> - Â Â Â set_page_private(page, (unsigned long) mapping);
> + Â Â Â set_page_private(page, (unsigned long)spool);
>
> Â Â Â Âvma_commit_reservation(h, vma, addr);
>
> @@ -2072,6 +2150,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
> Â{
> Â Â Â Âstruct hstate *h = hstate_vma(vma);
> Â Â Â Âstruct resv_map *reservations = vma_resv_map(vma);
> + Â Â Â struct hugepage_subpool *spool = subpool_vma(vma);
> Â Â Â Âunsigned long reserve;
> Â Â Â Âunsigned long start;
> Â Â Â Âunsigned long end;
> @@ -2087,7 +2166,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
>
> Â Â Â Â Â Â Â Âif (reserve) {
> Â Â Â Â Â Â Â Â Â Â Â Âhugetlb_acct_memory(h, -reserve);
> - Â Â Â Â Â Â Â Â Â Â Â hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
> + Â Â Â Â Â Â Â Â Â Â Â hugepage_subpool_put_pages(spool, reserve);
> Â Â Â Â Â Â Â Â}
> Â Â Â Â}
> Â}
> @@ -2316,7 +2395,7 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
> Â Â Â Â */
> Â Â Â Âaddress = address & huge_page_mask(h);
> Â Â Â Âpgoff = vma_hugecache_offset(h, vma, address);
> - Â Â Â mapping = (struct address_space *)page_private(page);
> + Â Â Â mapping = vma->vm_file->f_dentry->d_inode->i_mapping;
>
> Â Â Â Â/*
> Â Â Â Â * Take the mapping lock for the duration of the table walk. As
> @@ -2869,11 +2948,12 @@ int hugetlb_reserve_pages(struct inode *inode,
> Â{
> Â Â Â Âlong ret, chg;
> Â Â Â Âstruct hstate *h = hstate_inode(inode);
> + Â Â Â struct hugepage_subpool *spool = subpool_inode(inode);
>
> Â Â Â Â/*
> Â Â Â Â * Only apply hugepage reservation if asked. At fault time, an
> Â Â Â Â * attempt will be made for VM_NORESERVE to allocate a page
> - Â Â Â Â* and filesystem quota without using reserves
> + Â Â Â Â* without using reserves
> Â Â Â Â */
> Â Â Â Âif (vm_flags & VM_NORESERVE)
> Â Â Â Â Â Â Â Âreturn 0;
> @@ -2900,17 +2980,17 @@ int hugetlb_reserve_pages(struct inode *inode,
> Â Â Â Âif (chg < 0)
> Â Â Â Â Â Â Â Âreturn chg;
>
> - Â Â Â /* There must be enough filesystem quota for the mapping */
> - Â Â Â if (hugetlb_get_quota(inode->i_mapping, chg))
> + Â Â Â /* There must be enough pages in the subpool for the mapping */
> + Â Â Â if (hugepage_subpool_get_pages(spool, chg))
> Â Â Â Â Â Â Â Âreturn -ENOSPC;
>
> Â Â Â Â/*
> Â Â Â Â * Check enough hugepages are available for the reservation.
> - Â Â Â Â* Hand back the quota if there are not
> + Â Â Â Â* Hand the pages back to the subpool if there are not
> Â Â Â Â */
> Â Â Â Âret = hugetlb_acct_memory(h, chg);
> Â Â Â Âif (ret < 0) {
> - Â Â Â Â Â Â Â hugetlb_put_quota(inode->i_mapping, chg);
> + Â Â Â Â Â Â Â hugepage_subpool_put_pages(spool, chg);
> Â Â Â Â Â Â Â Âreturn ret;
> Â Â Â Â}
>
> @@ -2934,12 +3014,13 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
> Â{
> Â Â Â Âstruct hstate *h = hstate_inode(inode);
> Â Â Â Âlong chg = region_truncate(&inode->i_mapping->private_list, offset);
> + Â Â Â struct hugepage_subpool *spool = subpool_inode(inode);
>
> Â Â Â Âspin_lock(&inode->i_lock);
> Â Â Â Âinode->i_blocks -= (blocks_per_huge_page(h) * freed);
> Â Â Â Âspin_unlock(&inode->i_lock);
>
> - Â Â Â hugetlb_put_quota(inode->i_mapping, (chg - freed));
> + Â Â Â hugepage_subpool_put_pages(spool, (chg - freed));
> Â Â Â Âhugetlb_acct_memory(h, -(chg - freed));
> Â}
>
> --
> 1.7.9.1
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Next message: Guennadi Liakhovetski: "Re: [PATCH/RFC] dmaengine: add a slave parameter to __dma_request_channel()"
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In reply to: David Gibson: "[PATCH 2/2] hugepages: Fix use after free bug in "quota" handling"
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