Messages in this thread | | | Subject | Re: [Ocfs2-devel] [PATCH] fix crash on ocfs2_duplicate_clusters_by_page | From | Larry Chen <> | Date | Thu, 30 Aug 2018 10:40:51 +0800 |
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Hi Andrew and Changwei,
Thanks for your review, I'll propose a new version with comments corrected.
Thanks, Larry On 08/30/2018 10:29 AM, Changwei Ge wrote: > Hi Larry, > > Besides Andrew's comments, other parts of this patch look good to me. > > Thanks, > > Changwei > > > On 2018/8/30 6:25, Andrew Morton wrote: >> 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); >> >> _______________________________________________ >> Ocfs2-devel mailing list >> Ocfs2-devel@oss.oracle.com >> https://oss.oracle.com/mailman/listinfo/ocfs2-devel >
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