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 2457aec63745 ("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: Hugh Dickins <firstname.lastname@example.org>
Acked-by: Mel Gorman <email@example.com>
Cc: Johannes Weiner <firstname.lastname@example.org>
Cc: Vlastimil Babka <email@example.com>
Cc: Michal Hocko <firstname.lastname@example.org>
Cc: Dave Hansen <email@example.com>
Cc: Prabhakar Lad <firstname.lastname@example.org>
Signed-off-by: Andrew Morton <email@example.com>
Signed-off-by: Linus Torvalds <firstname.lastname@example.org>