RCU stalls in squashfs_readahead()

[Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>]

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Dear all,

I've noticed two similar RCU stalls with the similar call trace, both involving squashfs_readeahead().

Configuration is (excerpt):

CONFIG_KASAN_SHADOW_OFFSET=0xdffffc0000000000
CONFIG_HAVE_DEBUG_KMEMLEAK=y
CONFIG_DEBUG_KMEMLEAK=y
CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE=16000
# CONFIG_DEBUG_KMEMLEAK_TEST is not set
# CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF is not set
CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN=y
CONFIG_HAVE_ARCH_KASAN=y
CONFIG_HAVE_ARCH_KASAN_VMALLOC=y
CONFIG_CC_HAS_KASAN_GENERIC=y
CONFIG_KASAN=y
CONFIG_KASAN_GENERIC=y
CONFIG_KASAN_OUTLINE=y
# CONFIG_KASAN_INLINE is not set
CONFIG_KASAN_STACK=y
# CONFIG_KASAN_VMALLOC is not set
# CONFIG_KASAN_MODULE_TEST is not set

Do you think this is worthy of a bisect? I am not yet certain about being able to reproduce the stall, however it occurs at
great memory use and heavy swapping (I thought of experimenting with efficiency of multi-gen LRU in 6.1 with multimedia under heavy 
loads and low memory ...).

Here is the excerpt from dmesg:

[ 1326.301544] perf: interrupt took too long (3181 > 3178), lowering kernel.perf_event_max_sample_rate to 62750
[ 1347.269247] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 3-.... } 6 jiffies s: 1317 root: 0x8/.
[ 1347.269294] rcu: blocking rcu_node structures (internal RCU debug):
[ 1347.269310] Sending NMI from CPU 2 to CPUs 3:
[ 1347.269329] NMI backtrace for cpu 3
[ 1347.269343] CPU: 3 PID: 7907 Comm: Isolated Web Co Not tainted 6.1.0-rc5 #1
[ 1347.269357] Hardware name: LENOVO 82H8/LNVNB161216, BIOS GGCN49WW 07/21/2022
[ 1347.269363] RIP: 0010:__asan_load8+0x3e/0xb0
[ 1347.269386] Code: b8 00 00 00 00 00 00 00 ff eb 0a 48 b8 00 00 00 00 00 80 ff ff 48 39 f8 77 44 48 8d 47 07 48 89 c2 83 e2 07 48 
83 fa 07 75 1c <48> ba 00 00 00 00 00 fc ff df 48 c1 e8 03 0f b6 04 10 84 c0 75 30
[ 1347.269398] RSP: 0018:ffff888102eef288 EFLAGS: 00000246
[ 1347.269410] RAX: ffff888109280047 RBX: ffff8881157da0ca RCX: ffffffff8fca8434
[ 1347.269419] RDX: 0000000000000007 RSI: 0000000000000001 RDI: ffff888109280040
[ 1347.269427] RBP: ffff888102eef288 R08: 00000000000003ae R09: ffffed1021250de8
[ 1347.269435] R10: ffff888109286f39 R11: ffffed1021250de7 R12: 0000000000000155
[ 1347.269443] R13: ffffc9000122ff18 R14: ffff888109280000 R15: ffff888109280000
[ 1347.269451] FS:  00007efe541e9380(0000) GS:ffff888252f80000(0000) knlGS:0000000000000000
[ 1347.269462] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1347.269470] CR2: 00007fa7a15e2000 CR3: 000000013100a003 CR4: 0000000000770ee0
[ 1347.269479] PKRU: 55555554
[ 1347.269484] Call Trace:
[ 1347.269488]  <TASK>
[ 1347.269494]  lzma_main+0x3b4/0x12b0
[ 1347.269517]  lzma2_lzma+0x2dd/0x460
[ 1347.269535]  xz_dec_lzma2_run+0x11e/0xba0
[ 1347.269549]  ? __asan_load4+0x8/0xb0
[ 1347.269564]  ? crc32_le_base+0x179/0x250
[ 1347.269581]  xz_dec_run+0x57b/0x11a0
[ 1347.269600]  squashfs_xz_uncompress+0x196/0x370
[ 1347.269620]  squashfs_decompress+0x8e/0xd0
[ 1347.269633]  ? lzo_uncompress+0x400/0x400
[ 1347.269648]  squashfs_read_data+0x1e6/0x900
[ 1347.269662]  ? kmemleak_alloc+0x4b/0x80
[ 1347.269678]  ? squashfs_bio_read.isra.0+0x230/0x230
[ 1347.269694]  ? squashfs_page_actor_init_special+0x1bb/0x230
[ 1347.269710]  squashfs_readahead+0xa86/0xe70
[ 1347.269722]  ? put_pages_list+0x1e0/0x1e0
[ 1347.269747]  ? squashfs_fill_page+0x190/0x190
[ 1347.269763]  ? psi_task_change+0x106/0x130
[ 1347.269781]  ? raw_spin_rq_unlock+0x17/0x60
[ 1347.269796]  read_pages+0x12d/0x530
[ 1347.269814]  ? file_ra_state_init+0x60/0x60
[ 1347.269829]  ? xas_free_nodes+0x170/0x170
[ 1347.269844]  ? filemap_alloc_folio+0xcf/0x120
[ 1347.269863]  page_cache_ra_unbounded+0x1aa/0x280
[ 1347.269878]  ? __rcu_read_unlock+0x57/0x270
[ 1347.269898]  do_page_cache_ra+0x7c/0x90
[ 1347.269915]  page_cache_ra_order+0x3b4/0x420
[ 1347.269936]  filemap_fault+0x849/0xe40
[ 1347.269951]  ? read_cache_page_gfp+0x90/0x90
[ 1347.269970]  __do_fault+0x76/0x1e0
[ 1347.269984]  do_fault+0x1e5/0x6c0
[ 1347.269998]  __handle_mm_fault+0x905/0x1740
[ 1347.270015]  ? copy_page_range+0x2130/0x2130
[ 1347.270028]  ? mas_find+0x100/0x100
[ 1347.270050]  handle_mm_fault+0x11c/0x3b0
[ 1347.270065]  do_user_addr_fault+0x261/0x8b0
[ 1347.270084]  exc_page_fault+0x61/0xf0
[ 1347.270101]  asm_exc_page_fault+0x27/0x30
[ 1347.270115] RIP: 0033:0x7efe544ce8b4
[ 1347.270126] Code: d5 c4 e1 f9 7e d0 c4 e1 f9 7e d7 48 c1 f8 35 48 c1 ff 2e 48 89 c1 48 89 fe b8 ff 01 00 00 29 c8 83 e6 7f 48 8d 
0d ec 45 07 00 <c5> fb 10 04 f1 48 98 48 8d 0d fe 44 07 00 c5 fb 59 0c c1 c5 f3 59
[ 1347.270137] RSP: 002b:00007ffc019a6e30 EFLAGS: 00010206
[ 1347.270147] RAX: 0000000000000005 RBX: 00007ffc019a6f50 RCX: 00007efe54542ea0
[ 1347.270156] RDX: ffffffffbfefe12e RSI: 000000000000007b RDI: 000000000000fd7b
[ 1347.270164] RBP: 00007ffc019a6f58 R08: 00007ffc019a6f40 R09: 00000000006f71c0
[ 1347.270173] R10: 00007efe547fc500 R11: 00007efe54459b60 R12: 00007ffc019a7060
[ 1347.270181] R13: 00007ffc019a6f48 R14: 00007ffc019a7040 R15: 00007ffc019a6f40
[ 1347.270199]  </TASK>


[ 1534.865687] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 3-.... } 7 jiffies s: 1393 root: 0x8/.
[ 1534.865725] rcu: blocking rcu_node structures (internal RCU debug):
[ 1534.865735] Sending NMI from CPU 2 to CPUs 3:
[ 1534.865752] NMI backtrace for cpu 3
[ 1534.865762] CPU: 3 PID: 9629 Comm: FS Broker 9627 Not tainted 6.1.0-rc5 #1
[ 1534.865776] Hardware name: LENOVO 82H8/LNVNB161216, BIOS GGCN49WW 07/21/2022
[ 1534.865782] RIP: 0010:__asan_load4+0x8/0xb0
[ 1534.865802] Code: cc cc cc cc 48 c1 e8 03 80 3c 10 00 75 e9 5d c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 48 89 
e5 4c 8b 45 08 <48> 83 ff fb 77 63 eb 0f 0f 1f 00 48 b8 00 00 00 00 00 00 00 ff eb
[ 1534.865811] RSP: 0018:ffff88811fd3f288 EFLAGS: 00000246
[ 1534.865823] RAX: 0000000000000000 RBX: 000000000001d378 RCX: dffffc0000000000
[ 1534.865831] RDX: 0000000000000003 RSI: 000000000000077f RDI: ffff888109280080
[ 1534.865838] RBP: ffff88811fd3f288 R08: ffffffff8fca8622 R09: 000000000001d380
[ 1534.865847] R10: ffff888114694020 R11: ffffed102843b9ff R12: ffff888109280006
[ 1534.865854] R13: ffff888109280000 R14: ffff888109280000 R15: 0000000002bbab0b
[ 1534.865861] FS:  00007fe923eff700(0000) GS:ffff888252f80000(0000) knlGS:0000000000000000
[ 1534.865871] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1534.865878] CR2: 00007fe90fe90ac0 CR3: 0000000138d5c003 CR4: 0000000000770ee0
[ 1534.865885] PKRU: 55555554
[ 1534.865889] Call Trace:
[ 1534.865893]  <TASK>
[ 1534.865898]  lzma_main+0x5a2/0x12b0
[ 1534.865920]  lzma2_lzma+0x2dd/0x460
[ 1534.865935]  xz_dec_lzma2_run+0x11e/0xba0
[ 1534.865948]  ? crc32_le_base+0x58/0x250
[ 1534.865961]  ? crc32_le_base+0x1e3/0x250
[ 1534.865977]  xz_dec_run+0x57b/0x11a0
[ 1534.865995]  squashfs_xz_uncompress+0x196/0x370
[ 1534.866011]  squashfs_decompress+0x8e/0xd0
[ 1534.866022]  ? lzo_uncompress+0x400/0x400
[ 1534.866034]  squashfs_read_data+0x1e6/0x900
[ 1534.866047]  ? kmemleak_alloc+0x4b/0x80
[ 1534.866061]  ? squashfs_bio_read.isra.0+0x230/0x230
[ 1534.866074]  ? squashfs_page_actor_init_special+0x1bb/0x230
[ 1534.866087]  squashfs_readahead+0xa86/0xe70
[ 1534.866099]  ? xas_create+0x141/0x600
[ 1534.866119]  ? squashfs_fill_page+0x190/0x190
[ 1534.866136]  ? psi_task_change+0x106/0x130
[ 1534.866155]  ? raw_spin_rq_unlock+0x17/0x60
[ 1534.866171]  read_pages+0x12d/0x530
[ 1534.866186]  ? __kasan_check_read+0x11/0x20
[ 1534.866200]  ? folio_batch_add_and_move+0x8d/0xa0
[ 1534.866217]  ? file_ra_state_init+0x60/0x60
[ 1534.866231]  ? folio_add_lru+0x47/0x70
[ 1534.866249]  ? filemap_alloc_folio+0xcf/0x120
[ 1534.866267]  page_cache_ra_unbounded+0x1eb/0x280
[ 1534.866280]  ? __rcu_read_unlock+0x57/0x270
[ 1534.866297]  do_page_cache_ra+0x7c/0x90
[ 1534.866312]  page_cache_ra_order+0x3b4/0x420
[ 1534.866330]  filemap_fault+0x849/0xe40
[ 1534.866343]  ? read_cache_page_gfp+0x90/0x90
[ 1534.866359]  __do_fault+0x76/0x1e0
[ 1534.866372]  do_fault+0x1e5/0x6c0
[ 1534.866384]  __handle_mm_fault+0x905/0x1740
[ 1534.866399]  ? copy_page_range+0x2130/0x2130
[ 1534.866412]  ? mas_find+0x100/0x100
[ 1534.866428]  handle_mm_fault+0x11c/0x3b0
[ 1534.866443]  do_user_addr_fault+0x261/0x8b0
[ 1534.866456]  ? exit_to_user_mode_prepare+0x9b/0x190
[ 1534.866472]  exc_page_fault+0x61/0xf0
[ 1534.866486]  asm_exc_page_fault+0x27/0x30
[ 1534.866498] RIP: 0033:0x7fe93673dd00
[ 1534.866515] Code: Unable to access opcode bytes at 0x7fe93673dcd6.
[ 1534.866521] RSP: 002b:00007fe923efeea8 EFLAGS: 00010246
[ 1534.866532] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
[ 1534.866539] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
[ 1534.866545] RBP: 0000000000000000 R08: 0000000000000000 R09: 00007fe837100098
[ 1534.866553] R10: 00007fe868300de8 R11: 0000000000000217 R12: 00007fff95860b2e
[ 1534.866561] R13: 00007fff95860b2f R14: 00007fff95860bf8 R15: 00007fe923efef80
[ 1534.866576]  </TASK>

Thank you,
Mirsad

--
Mirsad Goran Todorovac
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
-- 
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
The European Union

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