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authorMichal Hocko <mhocko@suse.cz>2014-12-29 20:30:35 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-29 17:40:53 -0800
commit525f2d01368852ed91d220e0106bbfcefe5f1450 (patch)
tree79f3f549797713a011630dbbd06322d6fe908e68
parenta0d134d3e45980551e98d9b8ff11713e81622e02 (diff)
mm: get rid of radix tree gfp mask for pagecache_get_page
commit 45f87de57f8fad59302fd263dd81ffa4843b5b24 upstream. Commit 2457aec63745 ("mm: non-atomically mark page accessed during page cache allocation where possible") has added a separate parameter for specifying gfp mask for radix tree allocations. Not only this is less than optimal from the API point of view because it is error prone, it is also buggy currently because grab_cache_page_write_begin is using GFP_KERNEL for radix tree and if fgp_flags doesn't contain FGP_NOFS (mostly controlled by fs by AOP_FLAG_NOFS flag) but the mapping_gfp_mask has __GFP_FS cleared then the radix tree allocation wouldn't obey the restriction and might recurse into filesystem and cause deadlocks. This is the case for most filesystems unfortunately because only ext4 and gfs2 are using AOP_FLAG_NOFS. Let's simply remove radix_gfp_mask parameter because the allocation context is same for both page cache and for the radix tree. Just make sure that the radix tree gets only the sane subset of the mask (e.g. do not pass __GFP_WRITE). Long term it is more preferable to convert remaining users of AOP_FLAG_NOFS to use mapping_gfp_mask instead and simplify this interface even further. Reported-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/linux/pagemap.h13
-rw-r--r--mm/filemap.c20
2 files changed, 15 insertions, 18 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index ec054b4917df..fcebdda3651c 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -256,7 +256,7 @@ pgoff_t page_cache_prev_hole(struct address_space *mapping,
#define FGP_NOWAIT 0x00000020
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
- int fgp_flags, gfp_t cache_gfp_mask, gfp_t radix_gfp_mask);
+ int fgp_flags, gfp_t cache_gfp_mask);
/**
* find_get_page - find and get a page reference
@@ -271,13 +271,13 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
static inline struct page *find_get_page(struct address_space *mapping,
pgoff_t offset)
{
- return pagecache_get_page(mapping, offset, 0, 0, 0);
+ return pagecache_get_page(mapping, offset, 0, 0);
}
static inline struct page *find_get_page_flags(struct address_space *mapping,
pgoff_t offset, int fgp_flags)
{
- return pagecache_get_page(mapping, offset, fgp_flags, 0, 0);
+ return pagecache_get_page(mapping, offset, fgp_flags, 0);
}
/**
@@ -297,7 +297,7 @@ static inline struct page *find_get_page_flags(struct address_space *mapping,
static inline struct page *find_lock_page(struct address_space *mapping,
pgoff_t offset)
{
- return pagecache_get_page(mapping, offset, FGP_LOCK, 0, 0);
+ return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
}
/**
@@ -324,7 +324,7 @@ static inline struct page *find_or_create_page(struct address_space *mapping,
{
return pagecache_get_page(mapping, offset,
FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
- gfp_mask, gfp_mask & GFP_RECLAIM_MASK);
+ gfp_mask);
}
/**
@@ -345,8 +345,7 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
{
return pagecache_get_page(mapping, index,
FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
- mapping_gfp_mask(mapping),
- GFP_NOFS);
+ mapping_gfp_mask(mapping));
}
struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
diff --git a/mm/filemap.c b/mm/filemap.c
index 8aa817460cc7..217cfd3b3264 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -897,7 +897,7 @@ EXPORT_SYMBOL(find_lock_entry);
* @mapping: the address_space to search
* @offset: the page index
* @fgp_flags: PCG flags
- * @gfp_mask: gfp mask to use if a page is to be allocated
+ * @gfp_mask: gfp mask to use for the page cache data page allocation
*
* Looks up the page cache slot at @mapping & @offset.
*
@@ -916,7 +916,7 @@ EXPORT_SYMBOL(find_lock_entry);
* If there is a page cache page, it is returned with an increased refcount.
*/
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
- int fgp_flags, gfp_t cache_gfp_mask, gfp_t radix_gfp_mask)
+ int fgp_flags, gfp_t gfp_mask)
{
struct page *page;
@@ -953,13 +953,11 @@ no_page:
if (!page && (fgp_flags & FGP_CREAT)) {
int err;
if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
- cache_gfp_mask |= __GFP_WRITE;
- if (fgp_flags & FGP_NOFS) {
- cache_gfp_mask &= ~__GFP_FS;
- radix_gfp_mask &= ~__GFP_FS;
- }
+ gfp_mask |= __GFP_WRITE;
+ if (fgp_flags & FGP_NOFS)
+ gfp_mask &= ~__GFP_FS;
- page = __page_cache_alloc(cache_gfp_mask);
+ page = __page_cache_alloc(gfp_mask);
if (!page)
return NULL;
@@ -970,7 +968,8 @@ no_page:
if (fgp_flags & FGP_ACCESSED)
init_page_accessed(page);
- err = add_to_page_cache_lru(page, mapping, offset, radix_gfp_mask);
+ err = add_to_page_cache_lru(page, mapping, offset,
+ gfp_mask & GFP_RECLAIM_MASK);
if (unlikely(err)) {
page_cache_release(page);
page = NULL;
@@ -2460,8 +2459,7 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping,
fgp_flags |= FGP_NOFS;
page = pagecache_get_page(mapping, index, fgp_flags,
- mapping_gfp_mask(mapping),
- GFP_KERNEL);
+ mapping_gfp_mask(mapping));
if (page)
wait_for_stable_page(page);