Messages in this thread | | | Date | Wed, 29 Aug 2018 15:25:33 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] fix crash on ocfs2_duplicate_clusters_by_page |
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On Wed, 29 Aug 2018 15:47:40 +0800 Larry Chen <lchen@suse.com> wrote:
> ocfs2_duplicate_clusters_by_page may crash if one of extent's pages is dirty. > When a page has not been written back, it is still in dirty state. If > ocfs2_duplicate_clusters_by_page is called against the > dirty page, the crash happens. > > To fix this bug, we can just unlock the page and wait the page until > it's not dirty. > > The following is the buck trace dump: > > kernel BUG at /root/code/ocfs2/refcounttree.c:2961! > [exception RIP: ocfs2_duplicate_clusters_by_page+822] > __ocfs2_move_extent+0x80/0x450 [ocfs2] > ? __ocfs2_claim_clusters+0x130/0x250 [ocfs2] > ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2] > __ocfs2_move_extents_range+0x2a4/0x470 [ocfs2] > ocfs2_move_extents+0x180/0x3b0 [ocfs2] > ? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2] > ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2] > ocfs2_ioctl+0x253/0x640 [ocfs2] > do_vfs_ioctl+0x90/0x5f0 > SyS_ioctl+0x74/0x80 > do_syscall_64+0x74/0x140 > entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > > --- a/fs/ocfs2/refcounttree.c > +++ b/fs/ocfs2/refcounttree.c > @@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle, > if (map_end & (PAGE_SIZE - 1)) > to = map_end & (PAGE_SIZE - 1); > > +retry: > page = find_or_create_page(mapping, page_index, GFP_NOFS); > if (!page) { > ret = -ENOMEM; > @@ -2957,8 +2958,15 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle, > * In case PAGE_SIZE <= CLUSTER_SIZE, This page > * can't be dirtied before we CoW it out. > */
Looks sane, but the below change shows that the above comment is untrue. Can we please update the comment as well?
> - if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) > - BUG_ON(PageDirty(page)); > + if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) { > + if (PageDirty(page)) { > + /* > + * write_on_page will unlock the page on return > + */ > + ret = write_one_page(page); > + goto retry; > + } > + } > > if (!PageUptodate(page)) { > ret = block_read_full_page(page, ocfs2_get_block);
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