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SubjectRe: list corruption in deferred_split_scan()
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On 7/15/19 2:23 PM, Qian Cai wrote:
> On Fri, 2019-07-12 at 12:12 -0700, Yang Shi wrote:
>>> Another possible lead is that without reverting the those commits below,
>>> kdump
>>> kernel would always also crash in shrink_slab_memcg() at this line,
>>>
>>> map = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_map, true);
>> This looks a little bit weird. It seems nodeinfo[nid] is NULL? I didn't
>> think of where nodeinfo was freed but memcg was still online. Maybe a
>> check is needed:
> Actually, "memcg" is NULL.

It sounds weird. shrink_slab() is called in mem_cgroup_iter which does
pin the memcg. So, the memcg should not go away.

>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index a0301ed..bacda49 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -602,6 +602,9 @@ static unsigned long shrink_slab_memcg(gfp_t
>> gfp_mask, int nid,
>>          if (!mem_cgroup_online(memcg))
>>                  return 0;
>>
>> +       if (!memcg->nodeinfo[nid])
>> +               return 0;
>> +
>>          if (!down_read_trylock(&shrinker_rwsem))
>>                  return 0;
>>
>>> [    9.072036][    T1] BUG: KASAN: null-ptr-deref in shrink_slab+0x111/0x440
>>> [    9.072036][    T1] Read of size 8 at addr 0000000000000dc8 by task
>>> swapper/0/1
>>> [    9.072036][    T1]
>>> [    9.072036][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.0-next-
>>> 20190711+ #10
>>> [    9.072036][    T1] Hardware name: HPE ProLiant DL385 Gen10/ProLiant
>>> DL385
>>> Gen10, BIOS A40 01/25/2019
>>> [    9.072036][    T1] Call Trace:
>>> [    9.072036][    T1]  dump_stack+0x62/0x9a
>>> [    9.072036][    T1]  __kasan_report.cold.4+0xb0/0xb4
>>> [    9.072036][    T1]  ? unwind_get_return_address+0x40/0x50
>>> [    9.072036][    T1]  ? shrink_slab+0x111/0x440
>>> [    9.072036][    T1]  kasan_report+0xc/0xe
>>> [    9.072036][    T1]  __asan_load8+0x71/0xa0
>>> [    9.072036][    T1]  shrink_slab+0x111/0x440
>>> [    9.072036][    T1]  ? mem_cgroup_iter+0x98/0x840
>>> [    9.072036][    T1]  ? unregister_shrinker+0x110/0x110
>>> [    9.072036][    T1]  ? kasan_check_read+0x11/0x20
>>> [    9.072036][    T1]  ? mem_cgroup_protected+0x39/0x260
>>> [    9.072036][    T1]  shrink_node+0x31e/0xa30
>>> [    9.072036][    T1]  ? shrink_node_memcg+0x1560/0x1560
>>> [    9.072036][    T1]  ? ktime_get+0x93/0x110
>>> [    9.072036][    T1]  do_try_to_free_pages+0x22f/0x820
>>> [    9.072036][    T1]  ? shrink_node+0xa30/0xa30
>>> [    9.072036][    T1]  ? kasan_check_read+0x11/0x20
>>> [    9.072036][    T1]  ? check_chain_key+0x1df/0x2e0
>>> [    9.072036][    T1]  try_to_free_pages+0x242/0x4d0
>>> [    9.072036][    T1]  ? do_try_to_free_pages+0x820/0x820
>>> [    9.072036][    T1]  __alloc_pages_nodemask+0x9ce/0x1bc0
>>> [    9.072036][    T1]  ? gfp_pfmemalloc_allowed+0xc0/0xc0
>>> [    9.072036][    T1]  ? unwind_dump+0x260/0x260
>>> [    9.072036][    T1]  ? kernel_text_address+0x33/0xc0
>>> [    9.072036][    T1]  ? arch_stack_walk+0x8f/0xf0
>>> [    9.072036][    T1]  ? ret_from_fork+0x22/0x40
>>> [    9.072036][    T1]  alloc_page_interleave+0x18/0x130
>>> [    9.072036][    T1]  alloc_pages_current+0xf6/0x110
>>> [    9.072036][    T1]  allocate_slab+0x600/0x11f0
>>> [    9.072036][    T1]  new_slab+0x46/0x70
>>> [    9.072036][    T1]  ___slab_alloc+0x5d4/0x9c0
>>> [    9.072036][    T1]  ? create_object+0x3a/0x3e0
>>> [    9.072036][    T1]  ? fs_reclaim_acquire.part.15+0x5/0x30
>>> [    9.072036][    T1]  ? ___might_sleep+0xab/0xc0
>>> [    9.072036][    T1]  ? create_object+0x3a/0x3e0
>>> [    9.072036][    T1]  __slab_alloc+0x12/0x20
>>> [    9.072036][    T1]  ? __slab_alloc+0x12/0x20
>>> [    9.072036][    T1]  kmem_cache_alloc+0x32a/0x400
>>> [    9.072036][    T1]  create_object+0x3a/0x3e0
>>> [    9.072036][    T1]  kmemleak_alloc+0x71/0xa0
>>> [    9.072036][    T1]  kmem_cache_alloc+0x272/0x400
>>> [    9.072036][    T1]  ? kasan_check_read+0x11/0x20
>>> [    9.072036][    T1]  ? do_raw_spin_unlock+0xa8/0x140
>>> [    9.072036][    T1]  acpi_ps_alloc_op+0x76/0x122
>>> [    9.072036][    T1]  acpi_ds_execute_arguments+0x2f/0x18d
>>> [    9.072036][    T1]  acpi_ds_get_package_arguments+0x7d/0x84
>>> [    9.072036][    T1]  acpi_ns_init_one_package+0x33/0x61
>>> [    9.072036][    T1]  acpi_ns_init_one_object+0xfc/0x189
>>> [    9.072036][    T1]  acpi_ns_walk_namespace+0x114/0x1f2
>>> [    9.072036][    T1]  ? acpi_ns_init_one_package+0x61/0x61
>>> [    9.072036][    T1]  ? acpi_ns_init_one_package+0x61/0x61
>>> [    9.072036][    T1]  acpi_walk_namespace+0x9e/0xcb
>>> [    9.072036][    T1]  ? acpi_sleep_proc_init+0x36/0x36
>>> [    9.072036][    T1]  acpi_ns_initialize_objects+0x99/0xed
>>> [    9.072036][    T1]  ? acpi_ns_find_ini_methods+0xa2/0xa2
>>> [    9.072036][    T1]  ? acpi_tb_load_namespace+0x2dc/0x2eb
>>> [    9.072036][    T1]  acpi_load_tables+0x61/0x80
>>> [    9.072036][    T1]  acpi_init+0x10d/0x44b
>>> [    9.072036][    T1]  ? acpi_sleep_proc_init+0x36/0x36
>>> [    9.072036][    T1]  ? bus_uevent_filter+0x16/0x30
>>> [    9.072036][    T1]  ? kobject_uevent_env+0x109/0x980
>>> [    9.072036][    T1]  ? kernfs_get+0x13/0x20
>>> [    9.072036][    T1]  ? kobject_uevent+0xb/0x10
>>> [    9.072036][    T1]  ? kset_register+0x31/0x50
>>> [    9.072036][    T1]  ? kset_create_and_add+0x9f/0xd0
>>> [    9.072036][    T1]  ? acpi_sleep_proc_init+0x36/0x36
>>> [    9.072036][    T1]  do_one_initcall+0xfe/0x45a
>>> [    9.072036][    T1]  ? initcall_blacklisted+0x150/0x150
>>> [    9.072036][    T1]  ? rwsem_down_read_slowpath+0x930/0x930
>>> [    9.072036][    T1]  ? kasan_check_write+0x14/0x20
>>> [    9.072036][    T1]  ? up_write+0x6b/0x190
>>> [    9.072036][    T1]  kernel_init_freeable+0x614/0x6a7
>>> [    9.072036][    T1]  ? rest_init+0x188/0x188
>>> [    9.072036][    T1]  kernel_init+0x11/0x138
>>> [    9.072036][    T1]  ? rest_init+0x188/0x188
>>> [    9.072036][    T1]  ret_from_fork+0x22/0x40
>>> [    9.072036][    T1]
>>> ==================================================================
>>> [    9.072036][    T1] Disabling lock debugging due to kernel taint
>>> [    9.145712][    T1] BUG: kernel NULL pointer dereference, address:
>>> 0000000000000dc8
>>> [    9.152036][    T1] #PF: supervisor read access in kernel mode
>>> [    9.152036][    T1] #PF: error_code(0x0000) - not-present page
>>> [    9.152036][    T1] PGD 0 P4D 0
>>> [    9.152036][    T1] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
>>> [    9.152036][    T1] CPU: 0 PID: 1 Comm: swapper/0 Tainted:
>>> G    B             5.2.0-next-20190711+ #10
>>> [    9.152036][    T1] Hardware name: HPE ProLiant DL385 Gen10/ProLiant
>>> DL385
>>> Gen10, BIOS A40 01/25/2019
>>> [    9.152036][    T1] RIP: 0010:shrink_slab+0x111/0x440
>>> [    9.152036][    T1] Code: c7 20 8d 44 82 e8 7f 8b e8 ff 85 c0 0f 84 e2 02
>>> 00
>>> 00 4c 63 a5 4c ff ff ff 49 81 c4 b8 01 00 00 4b 8d 7c e6 08 e8 3f 07 0e 00
>>> <4f>
>>> 8b 64 e6 08 49 8d bc 24 20 03 00 00 e8 2d 07 0e 00 49 8b 84 24
>>> [    9.152036][    T1] RSP: 0018:ffff88905757f100 EFLAGS: 00010282
>>> [    9.152036][    T1] RAX: 0000000000000000 RBX: ffff88905757f1b0 RCX:
>>> ffffffff8112f288
>>> [    9.152036][    T1] RDX: 1ffffffff049c088 RSI: dffffc0000000000 RDI:
>>> ffffffff824e0440
>>> [    9.152036][    T1] RBP: ffff88905757f1d8 R08: fffffbfff049c089 R09:
>>> fffffbfff049c088
>>> [    9.152036][    T1] R10: fffffbfff049c088 R11: ffffffff824e0443 R12:
>>> 00000000000001b8
>>> [    9.152036][    T1] R13: 0000000000000000 R14: 0000000000000000 R15:
>>> ffff88905757f440
>>> [    9.152036][    T1] FS:  0000000000000000(0000) GS:ffff889062800000(0000)
>>> knlGS:0000000000000000
>>> [    9.152036][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [    9.152036][    T1] CR2: 0000000000000dc8 CR3: 0000001070212000 CR4:
>>> 00000000001406b0
>>> [    9.152036][    T1] Call Trace:
>>> [    9.152036][    T1]  ? mem_cgroup_iter+0x98/0x840
>>> [    9.152036][    T1]  ? unregister_shrinker+0x110/0x110
>>> [    9.152036][    T1]  ? kasan_check_read+0x11/0x20
>>> [    9.152036][    T1]  ? mem_cgroup_protected+0x39/0x260
>>> [    9.152036][    T1]  shrink_node+0x31e/0xa30
>>> [    9.152036][    T1]  ? shrink_node_memcg+0x1560/0x1560
>>> [    9.152036][    T1]  ? ktime_get+0x93/0x110
>>> [    9.152036][    T1]  do_try_to_free_pages+0x22f/0x820
>>> [    9.152036][    T1]  ? shrink_node+0xa30/0xa30
>>> [    9.152036][    T1]  ? kasan_check_read+0x11/0x20
>>> [    9.152036][    T1]  ? check_chain_key+0x1df/0x2e0
>>> [    9.152036][    T1]  try_to_free_pages+0x242/0x4d0
>>> [    9.152036][    T1]  ? do_try_to_free_pages+0x820/0x820
>>> [    9.152036][    T1]  __alloc_pages_nodemask+0x9ce/0x1bc0
>>> [    9.152036][    T1]  ? gfp_pfmemalloc_allowed+0xc0/0xc0
>>> [    9.152036][    T1]  ? unwind_dump+0x260/0x260
>>> [    9.152036][    T1]  ? kernel_text_address+0x33/0xc0
>>> [    9.152036][    T1]  ? arch_stack_walk+0x8f/0xf0
>>> [    9.152036][    T1]  ? ret_from_fork+0x22/0x40
>>> [    9.152036][    T1]  alloc_page_interleave+0x18/0x130
>>> [    9.152036][    T1]  alloc_pages_current+0xf6/0x110
>>> [    9.152036][    T1]  allocate_slab+0x600/0x11f0
>>> [    9.152036][    T1]  new_slab+0x46/0x70
>>> [    9.152036][    T1]  ___slab_alloc+0x5d4/0x9c0
>>> [    9.152036][    T1]  ? create_object+0x3a/0x3e0
>>> [    9.152036][    T1]  ? fs_reclaim_acquire.part.15+0x5/0x30
>>> [    9.152036][    T1]  ? ___might_sleep+0xab/0xc0
>>> [    9.152036][    T1]  ? create_object+0x3a/0x3e0
>>> [    9.152036][    T1]  __slab_alloc+0x12/0x20
>>> [    9.152036][    T1]  ? __slab_alloc+0x12/0x20
>>> [    9.152036][    T1]  kmem_cache_alloc+0x32a/0x400
>>> [    9.152036][    T1]  create_object+0x3a/0x3e0
>>> [    9.152036][    T1]  kmemleak_alloc+0x71/0xa0
>>> [    9.152036][    T1]  kmem_cache_alloc+0x272/0x400
>>> [    9.152036][    T1]  ? kasan_check_read+0x11/0x20
>>> [    9.152036][    T1]  ? do_raw_spin_unlock+0xa8/0x140
>>> [    9.152036][    T1]  acpi_ps_alloc_op+0x76/0x122
>>> [    9.152036][    T1]  acpi_ds_execute_arguments+0x2f/0x18d
>>> [    9.152036][    T1]  acpi_ds_get_package_arguments+0x7d/0x84
>>> [    9.152036][    T1]  acpi_ns_init_one_package+0x33/0x61
>>> [    9.152036][    T1]  acpi_ns_init_one_object+0xfc/0x189
>>> [    9.152036][    T1]  acpi_ns_walk_namespace+0x114/0x1f2
>>> [    9.152036][    T1]  ? acpi_ns_init_one_package+0x61/0x61
>>> [    9.152036][    T1]  ? acpi_ns_init_one_package+0x61/0x61
>>> [    9.152036][    T1]  acpi_walk_namespace+0x9e/0xcb
>>> [    9.152036][    T1]  ? acpi_sleep_proc_init+0x36/0x36
>>> [    9.152036][    T1]  acpi_ns_initialize_objects+0x99/0xed
>>> [    9.152036][    T1]  ? acpi_ns_find_ini_methods+0xa2/0xa2
>>> [    9.152036][    T1]  ? acpi_tb_load_namespace+0x2dc/0x2eb
>>> [    9.152036][    T1]  acpi_load_tables+0x61/0x80
>>> [    9.152036][    T1]  acpi_init+0x10d/0x44b
>>> [    9.152036][    T1]  ? acpi_sleep_proc_init+0x36/0x36
>>> [    9.152036][    T1]  ? bus_uevent_filter+0x16/0x30
>>> [    9.152036][    T1]  ? kobject_uevent_env+0x109/0x980
>>> [    9.152036][    T1]  ? kernfs_get+0x13/0x20
>>> [    9.152036][    T1]  ? kobject_uevent+0xb/0x10
>>> [    9.152036][    T1]  ? kset_register+0x31/0x50
>>> [    9.152036][    T1]  ? kset_create_and_add+0x9f/0xd0
>>> [    9.152036][    T1]  ? acpi_sleep_proc_init+0x36/0x36
>>> [    9.152036][    T1]  do_one_initcall+0xfe/0x45a
>>> [    9.152036][    T1]  ? initcall_blacklisted+0x150/0x150
>>> [    9.152036][    T1]  ? rwsem_down_read_slowpath+0x930/0x930
>>> [    9.152036][    T1]  ? kasan_check_write+0x14/0x20
>>> [    9.152036][    T1]  ? up_write+0x6b/0x190
>>> [    9.152036][    T1]  kernel_init_freeable+0x614/0x6a7
>>> [    9.152036][    T1]  ? rest_init+0x188/0x188
>>> [    9.152036][    T1]  kernel_init+0x11/0x138
>>> [    9.152036][    T1]  ? rest_init+0x188/0x188
>>> [    9.152036][    T1]  ret_from_fork+0x22/0x40
>>> [    9.152036][    T1] Modules linked in:
>>> [    9.152036][    T1] CR2: 0000000000000dc8
>>> [    9.152036][    T1] ---[ end trace 568acce4eca01945 ]---
>>> [    9.152036][    T1] RIP: 0010:shrink_slab+0x111/0x440
>>> [    9.152036][    T1] Code: c7 20 8d 44 82 e8 7f 8b e8 ff 85 c0 0f 84 e2 02
>>> 00
>>> 00 4c 63 a5 4c ff ff ff 49 81 c4 b8 01 00 00 4b 8d 7c e6 08 e8 3f 07 0e 00
>>> <4f>
>>> 8b 64 e6 08 49 8d bc 24 20 03 00 00 e8 2d 07 0e 00 49 8b 84 24
>>> [    9.152036][    T1] RSP: 0018:ffff88905757f100 EFLAGS: 00010282
>>> [    9.152036][    T1] RAX: 0000000000000000 RBX: ffff88905757f1b0 RCX:
>>> ffffffff8112f288
>>> [    9.152036][    T1] RDX: 1ffffffff049c088 RSI: dffffc0000000000 RDI:
>>> ffffffff824e0440
>>> [    9.152036][    T1] RBP: ffff88905757f1d8 R08: fffffbfff049c089 R09:
>>> fffffbfff049c088
>>> [    9.152036][    T1] R10: fffffbfff049c088 R11: ffffffff824e0443 R12:
>>> 00000000000001b8
>>> [    9.152036][    T1] R13: 0000000000000000 R14: 0000000000000000 R15:
>>> ffff88905757f440
>>> [    9.152036][    T1] FS:  0000000000000000(0000) GS:ffff889062800000(0000)
>>> knlGS:00000000
>>>

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