Similar to the recent commit [1] merged into the random and -next trees, it is not a good idea to call printk() with zone->lock held. The standard fix is to use printk_deferred() in those places, but memory offline will call dump_page() which need to defer after the lock. While at it, remove a similar but unnecessary debug printk() as well. [1] https://lore.kernel.org/lkml/1573679785-21068-1-git-send-email-cai@xxxxxx/ Signed-off-by: Qian Cai <cai@xxxxxx> --- include/linux/page-isolation.h | 2 +- mm/memory_hotplug.c | 2 +- mm/page_alloc.c | 12 +++++------- mm/page_isolation.c | 10 +++++++++- 4 files changed, 16 insertions(+), 10 deletions(-) diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h index 148e65a9c606..5d8ba078006f 100644 --- a/include/linux/page-isolation.h +++ b/include/linux/page-isolation.h @@ -34,7 +34,7 @@ static inline bool is_migrate_isolate(int migratetype) #define REPORT_FAILURE 0x2 bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype, - int flags); + int flags, char *dump); void set_pageblock_migratetype(struct page *page, int migratetype); int move_freepages_block(struct zone *zone, struct page *page, int migratetype, int *num_movable); diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 7a6de9b0dcab..f10928538fa3 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1149,7 +1149,7 @@ static bool is_pageblock_removable_nolock(unsigned long pfn) return false; return !has_unmovable_pages(zone, page, MIGRATE_MOVABLE, - MEMORY_OFFLINE); + MEMORY_OFFLINE, NULL); } /* Checks if this range of memory is likely to be hot-removable. */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index e56cd1f33242..b6bec3925e80 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8204,7 +8204,7 @@ void *__init alloc_large_system_hash(const char *tablename, * race condition. So you can't expect this function should be exact. */ bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype, - int flags) + int flags, char *dump) { unsigned long iter = 0; unsigned long pfn = page_to_pfn(page); @@ -8305,8 +8305,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int migratetype, return false; unmovable: WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); - if (flags & REPORT_FAILURE) - dump_page(pfn_to_page(pfn + iter), reason); + if (flags & REPORT_FAILURE) { + page = pfn_to_page(pfn + iter); + strscpy(dump, reason, 64); + } return true; } @@ -8711,10 +8713,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) BUG_ON(!PageBuddy(page)); order = page_order(page); offlined_pages += 1 << order; -#ifdef CONFIG_DEBUG_VM - pr_info("remove from free list %lx %d %lx\n", - pfn, 1 << order, end_pfn); -#endif del_page_from_free_area(page, &zone->free_area[order]); pfn += (1 << order); } diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 1f8b9dfecbe8..ce0fe3c1ceff 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -20,6 +20,7 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ struct zone *zone; unsigned long flags; int ret = -EBUSY; + char dump[64]; zone = page_zone(page); @@ -37,7 +38,8 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. * We just check MOVABLE pages. */ - if (!has_unmovable_pages(zone, page, migratetype, isol_flags)) { + if (!has_unmovable_pages(zone, page, migratetype, isol_flags, + dump)) { unsigned long nr_pages; int mt = get_pageblock_migratetype(page); @@ -54,6 +56,12 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ spin_unlock_irqrestore(&zone->lock, flags); if (!ret) drain_all_pages(zone); + else if (isol_flags & REPORT_FAILURE) + /* + * printk() with zone->lock held will guarantee to trigger a + * lockdep splat, so defer it here. + */ + dump_page(page, dump); return ret; } -- 2.21.0 (Apple Git-122.2)
