On Wed, Aug 03, 2011 at 05:59:03PM +0530, Kautuk Consul wrote: > Hi Mel, > > Sorry for the formatting. > > I forgot to include the following entire backtrace: > #> cp test_huge_file nfsmnt > kernel BUG at mm/page_alloc.c:849! > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > pgd = ce9f0000 > <SNIP> > Backtrace: > [<c00269ac>] (__bug+0x0/0x30) from [<c008e8b0>] > (move_freepages_block+0xd4/0x158) It's still horribly mangled and pretty much unreadable but at least we know where the bug is hitting. > <SNIP> > > Since I was testing on linux-2.6.35.9, line 849 in page_alloc.c is the > same line as you have mentioned: > BUG_ON(page_zone(start_page) != page_zone(end_page)) > > I reproduce this crash by altering the memory banks' memory ranges > such that they are not aligned to the SECTION_SIZE_BITS size. How are you altering the ranges? Are you somehow breaking the checks based on the information in stuct zone that is in move_freepages_block()? It no longer seems like a punching-hole-in-memmap problem. Can you investigate how and why the range of pages passed in to move_freepages() belong to different zones? Thanks. -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>