From 66d2f4d28cd030220e7ea2a628993fcabcb956d1 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Wed, 2 Jul 2014 15:22:38 -0700 Subject: [PATCH] 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 Acked-by: Mel Gorman Cc: Johannes Weiner Cc: Vlastimil Babka Cc: Michal Hocko Cc: Dave Hansen Cc: Prabhakar Lad Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 8f419cff9e34..1140f49b6ded 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1029,6 +1029,9 @@ repeat: goto failed; } + if (page && sgp == SGP_WRITE) + mark_page_accessed(page); + /* fallocated page? */ if (page && !PageUptodate(page)) { if (sgp != SGP_READ) @@ -1110,6 +1113,9 @@ repeat: shmem_recalc_inode(inode); spin_unlock(&info->lock); + if (sgp == SGP_WRITE) + mark_page_accessed(page); + delete_from_swap_cache(page); set_page_dirty(page); swap_free(swap); @@ -1136,6 +1142,9 @@ repeat: __SetPageSwapBacked(page); __set_page_locked(page); + if (sgp == SGP_WRITE) + init_page_accessed(page); + error = mem_cgroup_charge_file(page, current->mm, gfp & GFP_RECLAIM_MASK); 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) - init_page_accessed(*pagep); - return ret; + return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); } static int -- 2.30.2