On 12-08-17 11:22 AM, Herton Ronaldo Krzesinski wrote: > On Wed, Aug 15, 2012 at 03:47:58PM -0400, Paul Gortmaker wrote: >> From: Mitsuo Hayasaka <mitsuo.hayasaka...@hitachi.com> >> >> ------------------- >> This is a commit scheduled for the next v2.6.34 longterm release. >> http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git >> If you see a problem with using this for longterm, please comment. >> ------------------- >> >> commit f5252e009d5b87071a919221e4f6624184005368 upstream. >> >> The /proc/vmallocinfo shows information about vmalloc allocations in >> vmlist that is a linklist of vm_struct. It, however, may access pages >> field of vm_struct where a page was not allocated. This results in a null >> pointer access and leads to a kernel panic. >> >> Why this happens: In __vmalloc_node_range() called from vmalloc(), newly >> allocated vm_struct is added to vmlist at __get_vm_area_node() and then, >> some fields of vm_struct such as nr_pages and pages are set at >> __vmalloc_area_node(). In other words, it is added to vmlist before it is >> fully initialized. At the same time, when the /proc/vmallocinfo is read, >> it accesses the pages field of vm_struct according to the nr_pages field >> at show_numa_info(). Thus, a null pointer access happens. >> >> The patch adds the newly allocated vm_struct to the vmlist *after* it is >> fully initialized. So, it can avoid accessing the pages field with >> unallocated page when show_numa_info() is called. >> >> Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka...@hitachi.com> >> Cc: Andrew Morton <a...@linux-foundation.org> >> Cc: David Rientjes <rient...@google.com> >> Cc: Namhyung Kim <namhy...@gmail.com> >> Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> >> Cc: Jeremy Fitzhardinge <jeremy.fitzhardi...@citrix.com> >> Signed-off-by: Andrew Morton <a...@linux-foundation.org> >> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> >> [PG: .34 has VMALLOC_START/END vs. start/end in f5252e009d5] >> Signed-off-by: Paul Gortmaker <paul.gortma...@windriver.com> > [...] > > commit 1368edf0647ac112d8cfa6ce47257dc950c50f5c ("mm: vmalloc: check for > page allocation failure before vmlist insertion") addresses a regression > on this change, something to consider for inclusion in this stable > update as well.
Thanks Herton. I've added Willy to CC, since v2.6.32.49 added f5252e but does not have 1368edf0 yet in any 2.6.32.x Paul. -- > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
