| Message ID | 20191001144011.3801-5-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/memory_hotplug: Shrink zones before removing memory | expand |
On 02.10.19 02:06, kbuild test robot wrote: > Hi David, > > I love your patch! Perhaps something to improve: > > [auto build test WARNING on mmotm/master] > > url: https://github.com/0day-ci/linux/commits/David-Hildenbrand/mm-memory_hotplug-Shrink-zones-before-removing-memory/20191002-054310 > base: git://git.cmpxchg.org/linux-mmotm.git master > config: x86_64-randconfig-b002-201939 (attached as .config) > compiler: gcc-7 (Debian 7.4.0-13) 7.4.0 > reproduce: > # save the attached .config to linux build tree > make ARCH=x86_64 > > If you fix the issue, kindly add following tag > Reported-by: kbuild test robot <lkp@intel.com> > > All warnings (new ones prefixed by >>): > > In file included from include/asm-generic/bug.h:5:0, > from arch/x86/include/asm/bug.h:83, > from include/linux/bug.h:5, > from include/linux/mmdebug.h:5, > from include/linux/mm.h:9, > from mm/memory_hotplug.c:9: > mm/memory_hotplug.c: In function '__remove_zone': > mm/memory_hotplug.c:471:24: error: 'ZONE_DEVICE' undeclared (first use in this function); did you mean 'ZONE_MOVABLE'? > if (zone_idx(zone) == ZONE_DEVICE) > ^ > include/linux/compiler.h:58:52: note: in definition of macro '__trace_if_var' > #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) > ^~~~ >>> mm/memory_hotplug.c:471:2: note: in expansion of macro 'if' > if (zone_idx(zone) == ZONE_DEVICE) > ^~ > mm/memory_hotplug.c:471:24: note: each undeclared identifier is reported only once for each function it appears in > if (zone_idx(zone) == ZONE_DEVICE) > ^ > include/linux/compiler.h:58:52: note: in definition of macro '__trace_if_var' > #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) > ^~~~ >>> mm/memory_hotplug.c:471:2: note: in expansion of macro 'if' > if (zone_idx(zone) == ZONE_DEVICE) > ^~ > > vim +/if +471 mm/memory_hotplug.c > > 459 > 460 static void __remove_zone(struct zone *zone, unsigned long start_pfn, > 461 unsigned long nr_pages) > 462 { > 463 struct pglist_data *pgdat = zone->zone_pgdat; > 464 unsigned long flags; > 465 > 466 /* > 467 * Zone shrinking code cannot properly deal with ZONE_DEVICE. So > 468 * we will not try to shrink the zones - which is okay as > 469 * set_zone_contiguous() cannot deal with ZONE_DEVICE either way. > 470 */ > > 471 if (zone_idx(zone) == ZONE_DEVICE) > 472 return; > 473 > 474 pgdat_resize_lock(zone->zone_pgdat, &flags); > 475 shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); > 476 update_pgdat_span(pgdat); > 477 pgdat_resize_unlock(zone->zone_pgdat, &flags); > 478 } > 479 > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation > That should be easy to fix with some ifdef-ery :)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 86b4dc18e831..afed8331332b 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -331,7 +331,7 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone, unsigned long end_pfn) { for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(start_pfn))) + if (unlikely(!pfn_to_online_page(start_pfn))) continue; if (unlikely(pfn_to_nid(start_pfn) != nid)) @@ -356,7 +356,7 @@ static unsigned long find_biggest_section_pfn(int nid, struct zone *zone, /* pfn is the end pfn of a memory section. */ pfn = end_pfn - 1; for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(pfn))) + if (unlikely(!pfn_to_online_page(pfn))) continue; if (unlikely(pfn_to_nid(pfn) != nid)) @@ -415,7 +415,7 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, */ pfn = zone_start_pfn; for (; pfn < zone_end_pfn; pfn += PAGES_PER_SUBSECTION) { - if (unlikely(!pfn_valid(pfn))) + if (unlikely(!pfn_to_online_page(pfn))) continue; if (page_zone(pfn_to_page(pfn)) != zone) @@ -463,6 +463,14 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn, struct pglist_data *pgdat = zone->zone_pgdat; unsigned long flags; + /* + * Zone shrinking code cannot properly deal with ZONE_DEVICE. So + * we will not try to shrink the zones - which is okay as + * set_zone_contiguous() cannot deal with ZONE_DEVICE either way. + */ + if (zone_idx(zone) == ZONE_DEVICE) + return; + pgdat_resize_lock(zone->zone_pgdat, &flags); shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); update_pgdat_span(pgdat);
Let's limit shrinking to !ZONE_DEVICE so we can fix the current code. We should never try to touch the memmap of offline sections where we could have uninitialized memmaps and could trigger BUGs when calling page_to_nid() on poisoned pages. There is no reliable way to distinguish an uninitialized memmap from an initialized memmap that belongs to ZONE_DEVICE, as we don't have anything like SECTION_IS_ONLINE we can use similar to pfn_to_online_section() for !ZONE_DEVICE memory. E.g., set_zone_contiguous() similarly relies on pfn_to_online_section() and will therefore never set a ZONE_DEVICE zone consecutive. Stopping to shrink the ZONE_DEVICE therefore results in no observable changes, besides /proc/zoneinfo indicating different boundaries - something we can totally live with. Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug"), the memmap was initialized with 0 and the node with the right value. So the zone might be wrong but not garbage. After that commit, both the zone and the node will be garbage when touching uninitialized memmaps. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Dan Williams <dan.j.williams@intel.com> Fixes: d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug") Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- mm/memory_hotplug.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)