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tmpfs: pass gfp to shmem_getpage_gfp
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Make shmem_getpage() a wrapper, passing mapping_gfp_mask() down to
shmem_getpage_gfp(), which in turn passes gfp down to shmem_swp_alloc().

Change shmem_read_mapping_page_gfp() to use shmem_getpage_gfp() in the
CONFIG_SHMEM case; but leave tiny !SHMEM using read_cache_page_gfp().

Add a BUG_ON() in case anyone happens to call this on a non-shmem mapping;
though we might later want to let that case route to read_cache_page_gfp().

It annoys me to have these two almost-redundant args, gfp and fault_type:
I can't find a better way; but initialize fault_type only in shmem_fault().

Note that before, read_cache_page_gfp() was allocating i915_gem's pages
with __GFP_NORETRY as intended; but the corresponding swap vector pages
got allocated without it, leaving a small possibility of OOM.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@torvalds
Hugh Dickins authored and torvalds committed Jul 26, 2011
1 parent 71f0e07 commit 68da9f0
Showing 1 changed file with 44 additions and 23 deletions.
67 changes: 44 additions & 23 deletions mm/shmem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -127,8 +127,15 @@ static unsigned long shmem_default_max_inodes(void)
}
#endif

static int shmem_getpage(struct inode *inode, unsigned long idx,
struct page **pagep, enum sgp_type sgp, int *type);
static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);

static inline int shmem_getpage(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp, int *fault_type)
{
return shmem_getpage_gfp(inode, index, pagep, sgp,
mapping_gfp_mask(inode->i_mapping), fault_type);
}

static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
{
Expand Down Expand Up @@ -404,10 +411,12 @@ static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, uns
* @info: info structure for the inode
* @index: index of the page to find
* @sgp: check and recheck i_size? skip allocation?
* @gfp: gfp mask to use for any page allocation
*
* If the entry does not exist, allocate it.
*/
static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info,
unsigned long index, enum sgp_type sgp, gfp_t gfp)
{
struct inode *inode = &info->vfs_inode;
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Expand Down Expand Up @@ -435,7 +444,7 @@ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long
}

spin_unlock(&info->lock);
page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
page = shmem_dir_alloc(gfp);
spin_lock(&info->lock);

if (!page) {
Expand Down Expand Up @@ -1225,14 +1234,14 @@ static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
#endif

/*
* shmem_getpage - either get the page from swap or allocate a new one
* shmem_getpage_gfp - find page in cache, or get from swap, or allocate
*
* If we allocate a new one we do not mark it dirty. That's up to the
* vm. If we swap it in we mark it dirty since we also free the swap
* entry since a page cannot live in both the swap and page cache
*/
static int shmem_getpage(struct inode *inode, unsigned long idx,
struct page **pagep, enum sgp_type sgp, int *type)
static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx,
struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
Expand All @@ -1242,15 +1251,11 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
struct page *prealloc_page = NULL;
swp_entry_t *entry;
swp_entry_t swap;
gfp_t gfp;
int error;

if (idx >= SHMEM_MAX_INDEX)
return -EFBIG;

if (type)
*type = 0;

/*
* Normally, filepage is NULL on entry, and either found
* uptodate immediately, or allocated and zeroed, or read
Expand All @@ -1264,13 +1269,12 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
filepage = find_lock_page(mapping, idx);
if (filepage && PageUptodate(filepage))
goto done;
gfp = mapping_gfp_mask(mapping);
if (!filepage) {
/*
* Try to preload while we can wait, to not make a habit of
* draining atomic reserves; but don't latch on to this cpu.
*/
error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
if (error)
goto failed;
radix_tree_preload_end();
Expand All @@ -1290,7 +1294,7 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,

spin_lock(&info->lock);
shmem_recalc_inode(inode);
entry = shmem_swp_alloc(info, idx, sgp);
entry = shmem_swp_alloc(info, idx, sgp, gfp);
if (IS_ERR(entry)) {
spin_unlock(&info->lock);
error = PTR_ERR(entry);
Expand All @@ -1305,12 +1309,12 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
/* here we actually do the io */
if (type)
*type |= VM_FAULT_MAJOR;
if (fault_type)
*fault_type |= VM_FAULT_MAJOR;
swappage = shmem_swapin(swap, gfp, info, idx);
if (!swappage) {
spin_lock(&info->lock);
entry = shmem_swp_alloc(info, idx, sgp);
entry = shmem_swp_alloc(info, idx, sgp, gfp);
if (IS_ERR(entry))
error = PTR_ERR(entry);
else {
Expand Down Expand Up @@ -1461,7 +1465,7 @@ static int shmem_getpage(struct inode *inode, unsigned long idx,
SetPageSwapBacked(filepage);
}

entry = shmem_swp_alloc(info, idx, sgp);
entry = shmem_swp_alloc(info, idx, sgp, gfp);
if (IS_ERR(entry))
error = PTR_ERR(entry);
else {
Expand Down Expand Up @@ -1539,19 +1543,20 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
int error;
int ret;
int ret = VM_FAULT_LOCKED;

if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
return VM_FAULT_SIGBUS;

error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
if (error)
return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);

if (ret & VM_FAULT_MAJOR) {
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
}
return ret | VM_FAULT_LOCKED;
return ret;
}

#ifdef CONFIG_NUMA
Expand Down Expand Up @@ -3162,13 +3167,29 @@ int shmem_zero_setup(struct vm_area_struct *vma)
* suit tmpfs, since it may have pages in swapcache, and needs to find those
* for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
*
* Provide a stub for those callers to start using now, then later
* flesh it out to call shmem_getpage() with additional gfp mask, when
* shmem_file_splice_read() is added and shmem_readpage() is removed.
* i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
* with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
*/
struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp)
{
#ifdef CONFIG_SHMEM
struct inode *inode = mapping->host;
struct page *page = NULL;
int error;

BUG_ON(mapping->a_ops != &shmem_aops);
error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
if (error)
page = ERR_PTR(error);
else
unlock_page(page);
return page;
#else
/*
* The tiny !SHMEM case uses ramfs without swap
*/
return read_cache_page_gfp(mapping, index, gfp);
#endif
}
EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);

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