4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> commit d96b339f453997f2f08c52da3f41423be48c978f upstream. I saw the following BUG_ON triggered in a testcase where a process calls madvise(MADV_SOFT_OFFLINE) on thps, along with a background process that calls migratepages command repeatedly (doing ping-pong among different NUMA nodes) for the first process: Soft offlining page 0x60000 at 0x700000600000 __get_any_page: 0x60000 free buddy page page:ffffea0001800000 count:0 mapcount:-127 mapping: (null) index:0x1 flags: 0x1fffc0000000000() page dumped because: VM_BUG_ON_PAGE(atomic_read(&page->_count) == 0) ------------[ cut here ]------------ kernel BUG at /src/linux-dev/include/linux/mm.h:342! invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: cfg80211 rfkill crc32c_intel serio_raw virtio_balloon i2c_piix4 virtio_blk virtio_net ata_generic pata_acpi CPU: 3 PID: 3035 Comm: test_alloc_gene Tainted: G O 4.4.0-rc8-v4.4-rc8-160107-1501-00000-rc8+ #74 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: ffff88007c63d5c0 ti: ffff88007c210000 task.ti: ffff88007c210000 RIP: 0010:[<ffffffff8118998c>] [<ffffffff8118998c>] put_page+0x5c/0x60 RSP: 0018:ffff88007c213e00 EFLAGS: 00010246 Call Trace: put_hwpoison_page+0x4e/0x80 soft_offline_page+0x501/0x520 SyS_madvise+0x6bc/0x6f0 entry_SYSCALL_64_fastpath+0x12/0x6a Code: 8b fc ff ff 5b 5d c3 48 89 df e8 b0 fa ff ff 48 89 df 31 f6 e8 c6 7d ff ff 5b 5d c3 48 c7 c6 08 54 a2 81 48 89 df e8 a4 c5 01 00 <0f> 0b 66 90 66 66 66 66 90 55 48 89 e5 41 55 41 54 53 48 8b 47 RIP [<ffffffff8118998c>] put_page+0x5c/0x60 RSP <ffff88007c213e00> The root cause resides in get_any_page() which retries to get a refcount of the page to be soft-offlined. This function calls put_hwpoison_page(), expecting that the target page is putback to LRU list. But it can be also freed to buddy. So the second check need to care about such case. Fixes: af8fae7c0886 ("mm/memory-failure.c: clean up soft_offline_page()") Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Sasha Levin <sasha.levin@xxxxxxxxxx> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Jerome Marchand <jmarchan@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Steve Capper <steve.capper@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/memory-failure.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1572,7 +1572,7 @@ static int get_any_page(struct page *pag * Did it turn free? */ ret = __get_any_page(page, pfn, 0); - if (!PageLRU(page)) { + if (ret == 1 && !PageLRU(page)) { /* Drop page reference which is from __get_any_page() */ put_hwpoison_page(page); pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n", -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html