* [Patch 0/2] mm/memory_hotplug: fix hot remove bug
@ 2016-12-20 19:15 Yasuaki Ishimatsu
2016-12-20 19:16 ` [PATCH 1/2] mm/sparse: use page_private() to get page->private value Yasuaki Ishimatsu
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Yasuaki Ishimatsu @ 2016-12-20 19:15 UTC (permalink / raw)
To: linux-mm, linux-kernel
Here are two patches for memory hotplug:
Yasuaki Ishimatsu (2):
mm/sparse: use page_private() to get page->private value
mm/memory_hotplug: set magic number to page->freelsit instead
of page->lru.next
arch/x86/mm/init_64.c | 2 +-
mm/memory_hotplug.c | 4 ++--
mm/sparse.c | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)
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^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH 1/2] mm/sparse: use page_private() to get page->private value 2016-12-20 19:15 [Patch 0/2] mm/memory_hotplug: fix hot remove bug Yasuaki Ishimatsu @ 2016-12-20 19:16 ` Yasuaki Ishimatsu 2016-12-20 19:16 ` [PATCH 2/2] mm/memory_hotplug: set magic number to page->freelsit instead of page->lru.next Yasuaki Ishimatsu 2016-12-21 5:08 ` [Patch 0/2] mm/memory_hotplug: fix hot remove bug YASUAKI ISHIMATSU 2 siblings, 0 replies; 4+ messages in thread From: Yasuaki Ishimatsu @ 2016-12-20 19:16 UTC (permalink / raw) To: linux-mm, linux-kernel free_map_bootmem() uses page->private directly to set removing_section_nr argument. But to get page->private value, page_private() has been prepared. So free_map_bootmem() should use page_private() instead of page->private. Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> --- mm/sparse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/sparse.c b/mm/sparse.c index 1e168bf..c62b366 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -667,7 +667,7 @@ static void free_map_bootmem(struct page *memmap) BUG_ON(magic == NODE_INFO); maps_section_nr = pfn_to_section_nr(page_to_pfn(page)); - removing_section_nr = page->private; + removing_section_nr = page_private() /* * When this function is called, the removing section is -- 1.8.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] mm/memory_hotplug: set magic number to page->freelsit instead of page->lru.next 2016-12-20 19:15 [Patch 0/2] mm/memory_hotplug: fix hot remove bug Yasuaki Ishimatsu 2016-12-20 19:16 ` [PATCH 1/2] mm/sparse: use page_private() to get page->private value Yasuaki Ishimatsu @ 2016-12-20 19:16 ` Yasuaki Ishimatsu 2016-12-21 5:08 ` [Patch 0/2] mm/memory_hotplug: fix hot remove bug YASUAKI ISHIMATSU 2 siblings, 0 replies; 4+ messages in thread From: Yasuaki Ishimatsu @ 2016-12-20 19:16 UTC (permalink / raw) To: linux-mm, linux-kernel To identify that pages of page table are allocated from bootmem allocator, magic number sets to page->lru.next. But page->lru list is initialized in reserve_bootmem_region(). So when calling free_pagetable(), the function cannot find the magic number of pages. And free_pagetable() frees the pages by free_reserved_page() not put_page_bootmem(). But if the pages are allocated from bootmem allocator and used as page table, the pages have private flag. So before freeing the pages, we should clear the private flag by put_page_bootmem(). Before applying the commit 7bfec6f47bb0 ("mm, page_alloc: check multiple page fields with a single branch"), we could find the following visible issue: BUG: Bad page state in process kworker/u1024:1 page:ffffea103cfd8040 count:0 mapcount:0 mappi flags: 0x6fffff80000800(private) page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set bad because of flags: 0x800(private) <snip> Call Trace: [...] dump_stack+0x63/0x87 [...] bad_page+0x114/0x130 [...] free_pages_prepare+0x299/0x2d0 [...] free_hot_cold_page+0x31/0x150 [...] __free_pages+0x25/0x30 [...] free_pagetable+0x6f/0xb4 [...] remove_pagetable+0x379/0x7ff [...] vmemmap_free+0x10/0x20 [...] sparse_remove_one_section+0x149/0x180 [...] __remove_pages+0x2e9/0x4f0 [...] arch_remove_memory+0x63/0xc0 [...] remove_memory+0x8c/0xc0 [...] acpi_memory_device_remove+0x79/0xa5 [...] acpi_bus_trim+0x5a/0x8d [...] acpi_bus_trim+0x38/0x8d [...] acpi_device_hotplug+0x1b7/0x418 [...] acpi_hotplug_work_fn+0x1e/0x29 [...] process_one_work+0x152/0x400 [...] worker_thread+0x125/0x4b0 [...] ? __schedule+0x345/0x960 [...] ? rescuer_thread+0x380/0x380 [...] kthread+0xd8/0xf0 [...] ret_from_fork+0x22/0x40 [...] ? kthread_park+0x60/0x60 And the issue still silently occurs. Until freeing the pages of page table allocated from bootmem allocator, the page->freelist is never used. So the patch sets magic number to page->freelist instead of page->lru.next. Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> --- arch/x86/mm/init_64.c | 2 +- mm/memory_hotplug.c | 4 ++-- mm/sparse.c | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 963895f..b35e525 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -679,7 +679,7 @@ static void __meminit free_pagetable(struct page *page, int order) if (PageReserved(page)) { __ClearPageReserved(page); - magic = (unsigned long)page->lru.next; + magic = (unsigned long)page->freelist; if (magic == SECTION_INFO || magic == MIX_SECTION_INFO) { while (nr_pages--) put_page_bootmem(page++); diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index e43142c1..7e4047d 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -179,7 +179,7 @@ static void release_memory_resource(struct resource *res) void get_page_bootmem(unsigned long info, struct page *page, unsigned long type) { - page->lru.next = (struct list_head *) type; + page->freelist = (void *) type; SetPagePrivate(page); set_page_private(page, info); page_ref_inc(page); @@ -189,7 +189,7 @@ void put_page_bootmem(struct page *page) { unsigned long type; - type = (unsigned long) page->lru.next; + type = (unsigned long) page->freelist; BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE || type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE); diff --git a/mm/sparse.c b/mm/sparse.c index c62b366..862e609 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -662,7 +662,7 @@ static void free_map_bootmem(struct page *memmap) >> PAGE_SHIFT; for (i = 0; i < nr_pages; i++, page++) { - magic = (unsigned long) page->lru.next; + magic = (unsigned long) page->freelist; BUG_ON(magic == NODE_INFO); -- 1.8.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Patch 0/2] mm/memory_hotplug: fix hot remove bug 2016-12-20 19:15 [Patch 0/2] mm/memory_hotplug: fix hot remove bug Yasuaki Ishimatsu 2016-12-20 19:16 ` [PATCH 1/2] mm/sparse: use page_private() to get page->private value Yasuaki Ishimatsu 2016-12-20 19:16 ` [PATCH 2/2] mm/memory_hotplug: set magic number to page->freelsit instead of page->lru.next Yasuaki Ishimatsu @ 2016-12-21 5:08 ` YASUAKI ISHIMATSU 2 siblings, 0 replies; 4+ messages in thread From: YASUAKI ISHIMATSU @ 2016-12-21 5:08 UTC (permalink / raw) To: Linux MM, LKML [-- Attachment #1: Type: text/plain, Size: 514 bytes --] Self-NACK. I sent wrong patch-set... Thanks, Yasuaki Ishimatsu 2016-12-20 14:15 GMT-05:00 Yasuaki Ishimatsu <yasu.isimatu@gmail.com>: > Here are two patches for memory hotplug: > > Yasuaki Ishimatsu (2): > mm/sparse: use page_private() to get page->private value > mm/memory_hotplug: set magic number to page->freelsit instead > of page->lru.next > > arch/x86/mm/init_64.c | 2 +- > mm/memory_hotplug.c | 4 ++-- > mm/sparse.c | 4 ++-- > 3 files changed, 5 insertions(+), 5 deletions(-) > [-- Attachment #2: Type: text/html, Size: 1044 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-12-21 5:08 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2016-12-20 19:15 [Patch 0/2] mm/memory_hotplug: fix hot remove bug Yasuaki Ishimatsu 2016-12-20 19:16 ` [PATCH 1/2] mm/sparse: use page_private() to get page->private value Yasuaki Ishimatsu 2016-12-20 19:16 ` [PATCH 2/2] mm/memory_hotplug: set magic number to page->freelsit instead of page->lru.next Yasuaki Ishimatsu 2016-12-21 5:08 ` [Patch 0/2] mm/memory_hotplug: fix hot remove bug YASUAKI ISHIMATSU
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