On Sun, Apr 22, 2018 at 11:33:42AM +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > The patch below does not apply to the 4.4-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to <stable@xxxxxxxxxxxxxxx>. > > thanks, > > greg k-h > > ------------------ original commit in Linus's tree ------------------ > > From abc1be13fd113ddef5e2d807a466286b864caed3 Mon Sep 17 00:00:00 2001 > From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> > Date: Fri, 20 Apr 2018 14:56:20 -0700 > Subject: [PATCH] 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: > > __list_del_entry+0x30/0xd0 > list_lru_del+0xac/0x1ac > 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> > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > diff --git a/mm/filemap.c b/mm/filemap.c > index 9276bdb2343c..0604cb02e6f3 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -786,7 +786,7 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) > 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(struct page *page, > 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 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset, > 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 *file, pgoff_t offset, gfp_t gfp_mask) > 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) > It looks like c20cd45eb017 ("mm: allow GFP_{FS,IO} for page_cache_read page cache allocation") came in during 4.5 and reorganized a few things around the last section. If you pick that commit then this one, it will be clean (just tested on 4.4.128). Nathan