The patch titled
Subject: mm/filemap.c: fix NULL pointer in page_cache_tree_insert()
has been added to the -mm tree. Its filename is
fix-null-pointer-in-page_cache_tree_insert.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fix-null-pointer-in-page_cache_tree_insert.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fix-null-pointer-in-page_cache_tree_insert.patch
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------------------------------------------------------
From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Subject: mm/filemap.c: fix NULL pointer in page_cache_tree_insert()
f2fs specifies the __GFP_ZERO flag for allocating some of its pages.
Unfortunately, the page cache also uses the mapping's GFP flags for
allocating radix tree nodes. It always masked off the __GFP_HIGHMEM
flag, and masks off __GFP_ZERO in some paths, but not all. That causes
radix tree nodes to be allocated with a NULL list_head, which causes
backtraces like:
[<ffffff80086f4de0>] __list_del_entry+0x30/0xd0
[<ffffff8008362018>] list_lru_del+0xac/0x1ac
[<ffffff800830f04c>] page_cache_tree_insert+0xd8/0x110
The __GFP_DMA and __GFP_DMA32 flags would also be able to sneak through if
they are ever used. Fix them all by using GFP_RECLAIM_MASK at the
innermost location, and remove it from earlier in the callchain.
Link: http://lkml.kernel.org/r/20180411060320.14458-2-willy@xxxxxxxxxxxxx
Fixes: 449dd6984d0e ("mm: keep page cache radix tree nodes in check")
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Reported-by: Chris Fries <cfries@xxxxxxxxxx>
Debugged-by: Minchan Kim <minchan@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff -puN mm/filemap.c~fix-null-pointer-in-page_cache_tree_insert mm/filemap.c
--- a/mm/filemap.c~fix-null-pointer-in-page_cache_tree_insert
+++ a/mm/filemap.c
@@ -786,7 +786,7 @@ int replace_page_cache_page(struct page
VM_BUG_ON_PAGE(!PageLocked(new), new);
VM_BUG_ON_PAGE(new->mapping, new);
- error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
+ error = radix_tree_preload(gfp_mask & GFP_RECLAIM_MASK);
if (!error) {
struct address_space *mapping = old->mapping;
void (*freepage)(struct page *);
@@ -842,7 +842,7 @@ static int __add_to_page_cache_locked(st
return error;
}
- error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM);
+ error = radix_tree_maybe_preload(gfp_mask & GFP_RECLAIM_MASK);
if (error) {
if (!huge)
mem_cgroup_cancel_charge(page, memcg, false);
@@ -1585,8 +1585,7 @@ no_page:
if (fgp_flags & FGP_ACCESSED)
__SetPageReferenced(page);
- err = add_to_page_cache_lru(page, mapping, offset,
- gfp_mask & GFP_RECLAIM_MASK);
+ err = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
if (unlikely(err)) {
put_page(page);
page = NULL;
@@ -2387,7 +2386,7 @@ static int page_cache_read(struct file *
if (!page)
return -ENOMEM;
- ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask & GFP_KERNEL);
+ ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask);
if (ret == 0)
ret = mapping->a_ops->readpage(file, page);
else if (ret == -EEXIST)
_
Patches currently in -mm which might be from mawilcox@xxxxxxxxxxxxx are
fix-null-pointer-in-page_cache_tree_insert.patch
slab-__gfp_zero-is-incompatible-with-a-constructor.patch