On 12/16/2014 12:03 AM, [email protected] wrote: > From: James Custer <[email protected]> > Subject: mm: fix invalid use of pfn_valid_within in test_pages_in_a_zone > > Offlining memory by 'echo 0 > /sys/devices/system/memory/memory#/online' > or reading valid_zones 'cat > /sys/devices/system/memory/memory#/valid_zones' causes BUG: unable to > handle kernel paging request due to invalid use of pfn_valid_within. This > is due to a bug in test_pages_in_a_zone.
It would still be useful to show the BUG, and provide /proc/zoneinfo for us to see where are the corner cases. > In order to use pfn_valid_within within a MAX_ORDER_NR_PAGES block of > pages, a valid pfn within the block must first be found. There only needs > to be one valid pfn found in test_pages_in_a_zone in the first place. So > the fix is to replace pfn_valid_within with pfn_valid such that the first > valid pfn within the pageblock is found (if it exists). This works > independently of CONFIG_HOLES_IN_ZONE. > > Signed-off-by: James Custer <[email protected]> > Cc: KAMEZAWA Hiroyuki <[email protected]> > Cc: Russ Anderson <[email protected]> > Cc: <[email protected]> > Signed-off-by: Andrew Morton <[email protected]> > --- > > mm/memory_hotplug.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff -puN > mm/memory_hotplug.c~mm-fix-invalid-use-of-pfn_valid_within-in-test_pages_in_a_zone > mm/memory_hotplug.c > --- > a/mm/memory_hotplug.c~mm-fix-invalid-use-of-pfn_valid_within-in-test_pages_in_a_zone > +++ a/mm/memory_hotplug.c > @@ -1331,7 +1331,7 @@ int is_mem_section_removable(unsigned lo > } > > /* > - * Confirm all pages in a range [start, end) is belongs to the same zone. > + * Confirm all pages in a range [start, end) belong to the same zone. > */ > int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn) > { > @@ -1342,10 +1342,11 @@ int test_pages_in_a_zone(unsigned long s > for (pfn = start_pfn; > pfn < end_pfn; > pfn += MAX_ORDER_NR_PAGES) { > - i = 0; > - /* This is just a CONFIG_HOLES_IN_ZONE check.*/ > - while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i)) > - i++; > + /* Find the first valid pfn in this pageblock */ > + for (i = 0; i < MAX_ORDER_NR_PAGES; i++) { > + if (pfn_valid(pfn + i)) > + break; > + } > if (i == MAX_ORDER_NR_PAGES) > continue; > page = pfn_to_page(pfn + i); > _ > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"[email protected]";> [email protected] </a> > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
