Commit 66d2f4d2 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

shmem: fix init_page_accessed use to stop !PageLRU bug

Under shmem swapping load, I sometimes hit the VM_BUG_ON_PAGE(!PageLRU)
in isolate_lru_pages() at mm/vmscan.c:1281!

Commit 2457aec6

 ("mm: non-atomically mark page accessed during page
cache allocation where possible") looks like interrupted work-in-progress.

mm/filemap.c's call to init_page_accessed() is fine, but not mm/shmem.c's
- shmem_write_begin() is clearly wrong to use it after shmem_getpage(),
when the page is always visible in radix_tree, and often already on LRU.

Revert change to shmem_write_begin(), and use init_page_accessed() or
mark_page_accessed() appropriately for SGP_WRITE in shmem_getpage_gfp().

SGP_WRITE also covers shmem_symlink(), which did not mark_page_accessed()
before; but since many other filesystems use [__]page_symlink(), which did
and does mark the page accessed, consider this as rectifying an oversight.
Signed-off-by: default avatarHugh Dickins <>
Acked-by: default avatarMel Gorman <>
Cc: Johannes Weiner <>
Cc: Vlastimil Babka <>
Cc: Michal Hocko <>
Cc: Dave Hansen <>
Cc: Prabhakar Lad <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent d18bbc21
......@@ -1029,6 +1029,9 @@ repeat:
goto failed;
if (page && sgp == SGP_WRITE)
/* fallocated page? */
if (page && !PageUptodate(page)) {
if (sgp != SGP_READ)
......@@ -1110,6 +1113,9 @@ repeat:
if (sgp == SGP_WRITE)
......@@ -1136,6 +1142,9 @@ repeat:
if (sgp == SGP_WRITE)
error = mem_cgroup_charge_file(page, current->mm,
if (error)
......@@ -1412,13 +1421,9 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
int ret;
struct inode *inode = mapping->host;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
ret = shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
if (ret == 0 && *pagep)
return ret;
return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
static int
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