Re: kernel BUG at mm/huge_memory.c:2736(linux 5.10.29)

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,

> On Mon, Apr 12, 2021 at 3:07 AM Wang Yugui <wangyugui@e16-tech.com> wrote:
> >
> > Hi,
> >
> > kernel BUG at mm/huge_memory.c:2736(linux 5.10.29) is triggered
> > by some files write test.
> >
> > mm/huge_memory.c:
> >         if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
> >             pr_alert("total_mapcount: %u, page_count(): %u\n",
> >                     mapcount, count);
> >             if (PageTail(page))
> >                 dump_page(head, NULL);
> >             dump_page(page, "total_mapcount(head) > 0");
> > L2736:           BUG();
> >         }
> 
> We just can tell the mapcount of the page is not zero from the current
> log, it might mean the unmap_page() call is failed. It seems you have
> CONFIG_DEBUG_VM enabled, could you please paste more log? There is
> "VM_BUG_ON_PAGE(!unmap_success, page)" in unmap_page(). It should be
> able to tell us if unmap_page() is failed or not, or something else
> happened.


The kernel config:
$grep CONFIG_DEBUG_VM /boot/config-5.10.29-3.el7.x86_64
CONFIG_DEBUG_VM=y
# CONFIG_DEBUG_VM_VMACACHE is not set
# CONFIG_DEBUG_VM_RB is not set
# CONFIG_DEBUG_VM_PGFLAGS is not set
# CONFIG_DEBUG_VM_PGTABLE is not set

$grep HUGE /boot/config-5.10.29-3.el7.x86_64
CONFIG_CGROUP_HUGETLB=y
CONFIG_ARCH_WANT_GENERAL_HUGETLB=y
CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION=y
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE=y
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y
CONFIG_HAVE_ARCH_HUGE_VMAP=y
CONFIG_ARCH_WANT_HUGE_PMD_SHARE=y
CONFIG_TRANSPARENT_HUGEPAGE=y
# CONFIG_TRANSPARENT_HUGEPAGE_MADVISE is not set
CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y
CONFIG_HUGETLBFS=y
CONFIG_HUGETLB_PAGE=y

This problem hava a high reproduce frequence in a workstation, we need
a new RS232 cable to get more log, and it will take about a week.

Server: Dell Precision T7610
CPU: E5-2680v2 *2
Memory: 192G

the user case of our user-space application.
1)  write the files with the total size > 3 * memory size.
     the memory size > 128G
2) some CPU load, and some memory load.

the output of 'free -h' when our user-space application is running.
              total        used        free      shared  buff/cache   available
Mem:          188Gi        75Gi       7.9Gi        17Mi       104Gi       107Gi
Swap:            0B          0B          0B


Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2021/04/13

> 
> >
> > kernel version:5.10.29
> >
> > kernel BUG at mm/huge_memory.c:2736
> > invalid opcode: 0000 [#1] SMP NOPTI
> > CPU:9 pid:351 Comm: kswapd0 Tainted: G S
> > RIP: 0010:split_huge_page_to_list.cold.86+0x19/8x1b
> > ...
> > Call Trace:
> > ? shrink_inactive_list+0x241/0x3d0
> > deferred_split_scan+0x1ca/0x320
> > do_shrink_slab+0x20f/0x2c0
> > shrink_node+0x24b/0x6d0
> > balanced_pgdat+0x2db/0x550
> > kswaped+0x201/0x390
> > ? finish_wait+0x80/0x80
> > ? balance_pgdat+0x550/0x550
> > kthread+0x116/0x130
> > ? ktrhead_park+0x80/0x80
> > ret_from_fork+0x1f/0x30
> >
> > see OOPS.jpg for more info.
> >
> > Best Regards
> > Wang Yugui (wangyugui@e16-tech.com)
> > 2021/04/12
> >