On Fri, Jun 24, 2011 at 03:02:08PM +0800, Wengang Wang wrote: > mainline commit 2aa15890f3c191326678f1bd68af61ec6b8753ec > > mm: prevent concurrent unmap_mapping_range() on the same inode > > Michael Leun reported that running parallel opens on a fuse filesystem > can trigger a "kernel BUG at mm/truncate.c:475" > > Gurudas Pai reported the same bug on NFS. > > The reason is, unmap_mapping_range() is not prepared for more than > one concurrent invocation per inode. For example: > > thread1: going through a big range, stops in the middle of a vma and > stores the restart address in vm_truncate_count. > > thread2: comes in with a small (e.g. single page) unmap request on > the same vma, somewhere before restart_address, finds that the > vma was already unmapped up to the restart address and happily > returns without doing anything. > > Another scenario would be two big unmap requests, both having to > restart the unmapping and each one setting vm_truncate_count to its > own value. This could go on forever without any of them being able to > finish. > > Truncate and hole punching already serialize with i_mutex. Other > callers of unmap_mapping_range() do not, and it's difficult to get > i_mutex protection for all callers. In particular ->d_revalidate(), > which calls invalidate_inode_pages2_range() in fuse, may be called > with or without i_mutex. > > This patch adds a new mutex to 'struct address_space' to prevent > running multiple concurrent unmap_mapping_range() on the same mapping. > > [ We'll hopefully get rid of all this with the upcoming mm > preemptibility series by Peter Zijlstra, the "mm: Remove i_mmap_mutex > lockbreak" patch in particular. But that is for 2.6.39 ] > > > Adding this patch causes Kabi breakage. > > Signed-off-by: Miklos Szeredi <[email protected]> > Reported-by: Michael Leun <[email protected]> > Reported-by: Gurudas Pai <[email protected]> > Tested-by: Gurudas Pai <[email protected]> > Acked-by: Hugh Dickins <[email protected]> > Cc: [email protected] > Signed-off-by: Linus Torvalds <[email protected]> > Signed-off-by: Wengang Wang <[email protected]>
As this patch showed up in 2.6.39, I'm confused as to what you wanted me to do with it, so I've dropped it from my queue. greg k-h _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
