On Thu, Jun 16, 2016 at 03:50:31PM -0700, David Daney wrote: > From: David Daney <david.daney@xxxxxxxxxx> > > When the core THP code is modifying the permissions of a huge page it > calls pmd_modify(), which unfortunately was clearing the _PAGE_HUGE bit > of the page table entry. The result can be kernel messages like: > > mm/memory.c:397: bad pmd 000000040080004d. > mm/memory.c:397: bad pmd 00000003ff00004d. > mm/memory.c:397: bad pmd 000000040100004d. > > or: > > ------------[ cut here ]------------ > WARNING: at mm/mmap.c:3200 exit_mmap+0x150/0x158() > Modules linked in: ipv6 at24 octeon3_ethernet octeon_srio_nexus m25p80 > CPU: 12 PID: 1295 Comm: pmderr Not tainted 3.10.87-rt80-Cavium-Octeon #4 > Stack : 0000000040808000 0000000014009ce1 0000000000400004 ffffffff81076ba0 > 0000000000000000 0000000000000000 ffffffff85110000 0000000000000119 > 0000000000000004 0000000000000000 0000000000000119 43617669756d2d4f > 0000000000000000 ffffffff850fda40 ffffffff85110000 0000000000000000 > 0000000000000000 0000000000000009 ffffffff809207a0 0000000000000c80 > ffffffff80f1bf20 0000000000000001 000000ffeca36828 0000000000000001 > 0000000000000000 0000000000000001 000000ffeca7e700 ffffffff80886924 > 80000003fd7a0000 80000003fd7a39b0 80000003fdea8000 ffffffff80885780 > 80000003fdea8000 ffffffff80f12218 000000000000000c 000000000000050f > 0000000000000000 ffffffff80865c4c 0000000000000000 0000000000000000 > ... > Call Trace: > [<ffffffff80865c4c>] show_stack+0x6c/0xf8 > [<ffffffff80885780>] warn_slowpath_common+0x78/0xa8 > [<ffffffff809207a0>] exit_mmap+0x150/0x158 > [<ffffffff80882d44>] mmput+0x5c/0x110 > [<ffffffff8088b450>] do_exit+0x230/0xa68 > [<ffffffff8088be34>] do_group_exit+0x54/0x1d0 > [<ffffffff8088bfc0>] __wake_up_parent+0x0/0x18 > > ---[ end trace c7b38293191c57dc ]--- > BUG: Bad rss-counter state mm:80000003fa168000 idx:1 val:1536 > > Fix by not clearing _PAGE_HUGE bit. I resolved the conflict with my recent other fix for pmd_modify and just applied and pushed this. Ralf
