On 12/24/2015 08:12 PM, Dan Williams wrote: > On Thu, Dec 24, 2015 at 5:10 PM, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote: >> > On 12/24/2015 06:51 AM, Kirill A. Shutemov wrote: >>> >> This patch fixes regression caused by patch >>> >> "mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd" >>> >> >>> >> The patch makes pmd_trans_huge() check and "page = pmd_page(*pmd)" after >>> >> __split_huge_pmd_locked(). It can never succeed, since the pmd already >>> >> points to a page table. As result the page is never get munlocked. >>> >> >>> >> It causes crashes like this: >>> >> http://lkml.kernel.org/r/5661FBB6.6050307@xxxxxxxxxx >> > >> > So this patch didn't fix the issue for me. I've sent Kirill the trace >> > off-list, but it's essentially the same thing. > Can you send me the trace as well, and the reproducer? I don't have a simple reproducer, it reproduces rather quickly when running under trinity within a KVM guest running a kernel I've attached the config for. Here's the trace: [ 2885.040719] BUG: Bad page state in process kswapd0 pfn:ba000 [ 2885.040734] page:ffffea0002e80000 count:0 mapcount:0 mapping: (null) index:0x800 [ 2885.040745] flags: 0x9fffff80144008(uptodate|head|swapbacked|mlocked) [ 2885.040747] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set [ 2885.040749] bad because of flags: 0x100000(mlocked) [ 2885.040774] Modules linked in: [ 2885.040798] CPU: 0 PID: 3740 Comm: kswapd0 Not tainted 4.4.0-rc5-next-20151221-sasha-00026-g627e275-d irty #2758 [ 2885.040821] 0000000000000000 00000000b542da6d ffff8800c9c4f538 ffffffffa3045a14 [ 2885.040825] 0000000041b58ab3 ffffffffae666b8b ffffffffa3045969 ffff880559cc06fd [ 2885.040853] ffffea0002e80000 00000000b542da6d ffff8800c9c4f538 0000000000100000 [ 2885.040854] Call Trace: [ 2885.041027] [<ffffffffa3045a14>] dump_stack+0xab/0x117 [ 2885.041034] [<ffffffffa3045969>] ? _atomic_dec_and_lock+0xc9/0xc9 [ 2885.041067] [<ffffffffa16258b5>] bad_page+0x295/0x350 [ 2885.041160] [<ffffffffa1627c69>] free_pages_prepare+0x489/0x1650 [ 2885.041193] [<ffffffffa162fd13>] __free_pages_ok+0x43/0x230 [ 2885.041197] [<ffffffffa162ff92>] free_compound_page+0x92/0xa0 [ 2885.041207] [<ffffffffa1777af7>] free_transhuge_page+0x87/0x90 [ 2885.041215] [<ffffffffa164c4fc>] __put_compound_page+0xac/0xc0 [ 2885.041232] [<ffffffffa164c5ae>] __put_page+0x9e/0xb0 [ 2885.041236] [<ffffffffa177655b>] deferred_split_scan+0x7ab/0x7d0 [ 2885.041277] [<ffffffffa16582df>] shrink_slab+0x4af/0x660 [ 2885.041298] [<ffffffffa1665b4d>] shrink_zone+0x6bd/0xbf0 [ 2885.041320] [<ffffffffa1668582>] balance_pgdat+0x7f2/0xc00 [ 2885.041398] [<ffffffffa1669243>] kswapd+0x8b3/0xa10 [ 2885.041437] [<ffffffffa13bf8ce>] kthread+0x31e/0x330 [ 2885.041453] [<ffffffffabe1ad0f>] ret_from_fork+0x3f/0x70 Thanks, Sasha
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