From: Hugh Dickins Date: Thu, 24 Feb 2011 05:39:49 +0000 (-0800) Subject: mm: fix possible cause of a page_mapped BUG X-Git-Tag: v2.6.37.4~19 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dae781690ffa8c152cbdcdfaec404e53f7425535;p=pandora-kernel.git mm: fix possible cause of a page_mapped BUG commit a3e8cc643d22d2c8ed36b9be7d9c9ca21efcf7f7 upstream. Robert Swiecki reported a BUG_ON(page_mapped) from a fuzzer, punching a hole with madvise(,, MADV_REMOVE). That path is under mutex, and cannot be explained by lack of serialization in unmap_mapping_range(). Reviewing the code, I found one place where vm_truncate_count handling should have been updated, when I switched at the last minute from one way of managing the restart_addr to another: mremap move changes the virtual addresses, so it ought to adjust the restart_addr. But rather than exporting the notion of restart_addr from memory.c, or converting to restart_pgoff throughout, simply reset vm_truncate_count to 0 to force a rescan if mremap move races with preempted truncation. We have no confirmation that this fixes Robert's BUG, but it is a fix that's worth making anyway. Signed-off-by: Hugh Dickins Signed-off-by: Linus Torvalds Cc: Kerin Millar Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed