Re: cgroup and FALLOC_FL_PUNCH_HOLE: WARNING: CPU: 13 PID: 2438 at mm/page_counter.c:57 page_counter_uncharge+0x4b/0x5
From: Michal Privoznik
Date: Wed Oct 21 2020 - 08:57:13 EST
On 10/21/20 5:35 AM, Mike Kravetz wrote:
On 10/20/20 6:38 AM, David Hildenbrand wrote:
I'm bisecting the warning right now. Looks like it was introduced in v5.7.
I found the following bugs in the cgroup reservation accounting. The ones
in region_del are pretty obvious as the number of pages to uncharge would
always be zero. The one on alloc_huge_page needs racing code to expose.
With these fixes, my testing is showing consistent/correct results for
hugetlb reservation cgroup accounting.
It would be good if Mina (at least) would look these over. Would also
be interesting to know if these fixes address the bug seen with the qemu
use case.
I'm still doing more testing and code inspection to look for other issues.
From 861bcd7d0443f18a5fed3c3ddc5f1c71e78c4ef4 Mon Sep 17 00:00:00 2001
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Date: Tue, 20 Oct 2020 20:21:42 -0700
Subject: [PATCH] hugetlb_cgroup: fix reservation accounting
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/hugetlb.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 67fc6383995b..c92366313780 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -685,17 +685,17 @@ static long region_del(struct resv_map *resv, long f, long t)
}
if (f <= rg->from) { /* Trim beginning of region */
- del += t - rg->from;
- rg->from = t;
-
hugetlb_cgroup_uncharge_file_region(resv, rg,
t - rg->from);
- } else { /* Trim end of region */
- del += rg->to - f;
- rg->to = f;
+ del += t - rg->from;
+ rg->from = t;
+ } else { /* Trim end of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
rg->to - f);
+
+ del += rg->to - f;
+ rg->to = f;
}
}
@@ -2454,6 +2454,9 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
rsv_adjust = hugepage_subpool_put_pages(spool, 1);
hugetlb_acct_memory(h, -rsv_adjust);
+ if (deferred_reserve)
+ hugetlb_cgroup_uncharge_page_rsvd(hstate_index(h),
+ pages_per_huge_page(h), page);
}
return page;
I've applied, rebuilt and tested, but unfortunately I still hit the problem:
[ 6472.719047] ------------[ cut here ]------------
[ 6472.719052] WARNING: CPU: 6 PID: 11773 at mm/page_counter.c:57
page_counter_uncharge+0x33/0x40
[ 6472.719052] Modules linked in: kvm_amd amdgpu kvm btusb sp5100_tco
btrtl watchdog k10temp btbcm btintel mfd_core gpu_sched ttm
[ 6472.719057] CPU: 6 PID: 11773 Comm: CPU 3/KVM Not tainted
5.9.1-gentoo-x86_64 #1
[ 6472.719057] Hardware name: System manufacturer System Product
Name/PRIME X570-PRO, BIOS 1005 08/01/2019
[ 6472.719059] RIP: 0010:page_counter_uncharge+0x33/0x40
[ 6472.719060] Code: 48 85 ff 74 24 4c 89 c8 f0 48 0f c1 07 4c 29 c0 48
89 c1 48 89 c6 e8 7c fe ff ff 48 85 c9 78 0a 48 8b 7f 28 48 85 ff 75 dc
c3 <0f> 0b eb f2 66 0f 1f 84 00 00 00 00 00 48 8b 17 48 39 d6 72 41 41
[ 6472.719061] RSP: 0018:ffffc90000b77b40 EFLAGS: 00010286
[ 6472.719061] RAX: fffffffffffe9200 RBX: ffff888fb3b97b40 RCX:
fffffffffffe9200
[ 6472.719062] RDX: 0000000000000221 RSI: fffffffffffe9200 RDI:
ffff888fd8451dd0
[ 6472.719062] RBP: ffff888fb6990420 R08: 0000000000044200 R09:
fffffffffffbbe00
[ 6472.719062] R10: ffff888fb3b97b40 R11: 000000000000000a R12:
0000000000000001
[ 6472.719063] R13: 00000000000005df R14: 00000000000005de R15:
ffff888fb3b97b40
[ 6472.719063] FS: 00007fbd175fe700(0000) GS:ffff888fde980000(0000)
knlGS:0000000000000000
[ 6472.719064] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6472.719064] CR2: 00007fbd825101f0 CR3: 0000000fb5e41000 CR4:
0000000000350ee0
[ 6472.719065] Call Trace:
[ 6472.719067] hugetlb_cgroup_uncharge_file_region+0x46/0x70
[ 6472.719069] region_del+0x1ae/0x270
[ 6472.719070] hugetlb_unreserve_pages+0x32/0xa0
[ 6472.719072] remove_inode_hugepages+0x19d/0x3a0
[ 6472.719079] ? writeback_registers+0x45/0x60 [kvm]
[ 6472.719080] hugetlbfs_fallocate+0x3f2/0x4a0
[ 6472.719081] ? __mod_lruvec_state+0x1d/0x40
[ 6472.719081] ? __mod_memcg_lruvec_state+0x1b/0xe0
[ 6472.719083] ? __seccomp_filter+0x75/0x6a0
[ 6472.719084] vfs_fallocate+0x122/0x260
[ 6472.719085] __x64_sys_fallocate+0x39/0x60
[ 6472.719086] do_syscall_64+0x2d/0x40
[ 6472.719088] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 6472.719089] RIP: 0033:0x7fbe3cefcde7
[ 6472.719089] Code: 89 7c 24 08 48 89 4c 24 18 e8 45 fc f8 ff 41 89 c0
4c 8b 54 24 18 48 8b 54 24 10 b8 1d 01 00 00 8b 74 24 0c 8b 7c 24 08 0f
05 <48> 3d 00 f0 ff ff 77 41 44 89 c7 89 44 24 08 e8 75 fc f8 ff 8b 44
[ 6472.719090] RSP: 002b:00007fbd175fc7a0 EFLAGS: 00000293 ORIG_RAX:
000000000000011d
[ 6472.719090] RAX: ffffffffffffffda RBX: 00000000bbe00000 RCX:
00007fbe3cefcde7
[ 6472.719091] RDX: 00000000bbc00000 RSI: 0000000000000003 RDI:
000000000000001d
[ 6472.719091] RBP: 00007fbd175fc800 R08: 0000000000000000 R09:
0000000000000000
[ 6472.719091] R10: 0000000000200000 R11: 0000000000000293 R12:
00007ffeea066d2e
[ 6472.719092] R13: 00007ffeea066d2f R14: 00007fbd175fe700 R15:
00007fbd175fcdc0
[ 6472.719092] ---[ end trace c97dc6281a861980 ]---
Sorry,
Michal