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From:   "hoyoung seo" <hy50.seo@samsung.com>
To:     <andrey.konovalov@linux.dev>
Cc:     <akpm@linux-foundation.org>, <andreyknvl@gmail.com>,
        <andreyknvl@google.com>, <elver@google.com>, <eugenis@google.com>,
        <glider@google.com>, <kasan-dev@googlegroups.com>,
        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        <vbabka@suse.cz>, <bhoon95.kim@samsung.com>, <sc.suh@samsung.com>
Subject: Re: [PATCH v2 10/18] lib/stackdepot: rename handle and pool
 constants
Date:   Wed, 12 Apr 2023 15:05:58 +0900
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References: <CGME20230412060558epcas2p254358bbd869eec9fb9907db6abac459a@epcas2p2.samsung.com>
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+=23define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
+
+=23define DEPOT_VALID_BITS 1
+=23define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */
+=23define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER))
+=23define DEPOT_STACK_ALIGN 4
+=23define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_A=
LIGN)
+=23define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_VALID_BITS - =
=5C
+			       DEPOT_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS)
+=23define DEPOT_POOLS_CAP 8192

Increase DEPOT_POOLS_CAP size to 32768

+=23define DEPOT_MAX_POOLS =5C
+	(((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? =5C
+	 (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP)


Hi Andrey.

I have some question about DEPOT_MAX_POOLS.
Actually I didn't know where to post my question, so here it is.
I'm testing a feature of the UFS4.0 specification called MCQ,=20
the call stack looks like this and __stack_depot_save keeps printing warnin=
g messages.

=5B7:  OST-Normal-13:17476=5D ------------=5B cut here =5D------------
=5B7:  OST-Normal-13:17476=5D Stack depot reached limit capacity
=5B7:  OST-Normal-13:17476=5D pc : __stack_depot_save+0x464/0x46c
=5B7:  OST-Normal-13:17476=5D lr : __stack_depot_save+0x460/0x46c
=5B7:  OST-Normal-13:17476=5D sp : ffffffc008077730
=5B7:  OST-Normal-13:17476=5D x29: ffffffc008077750 x28: ffffffd00b78a000 x=
27: 0000000000000000
=5B7:  OST-Normal-13:17476=5D x26: 000000000009a7a4 x25: ffffff8914750000 x=
24: 000000004379a7a4
=5B7:  OST-Normal-13:17476=5D x23: 00000000000001f8 x22: 0000000000000210 x=
21: 000000000000003f
=5B7:  OST-Normal-13:17476=5D x20: ffffffc0080777b0 x19: 0000000000000000 x=
18: 0000000000001000
=5B7:  OST-Normal-13:17476=5D x17: 2065726568207475 x16: 00000000000000c3 x=
15: 2d2d2d2d2d2d2d20
=5B7:  OST-Normal-13:17476=5D x14: 5d36373437313a33 x13: 000000000059a740 x=
12: 000000000059a6f8
=5B7:  OST-Normal-13:17476=5D x11: 00000000ffffffff x10: ffffffb90aba9000 x=
9 : 008c3feffad60900
=5B7:  OST-Normal-13:17476=5D x8 : 008c3feffad60900 x7 : 000000000059a740 x=
6 : 000000000059a6f8
=5B7:  OST-Normal-13:17476=5D x5 : ffffffc008077438 x4 : ffffffd00b196970 x=
3 : ffffffd0092b313c
=5B7:  OST-Normal-13:17476=5D x2 : 0000000000000001 x1 : 0000000000000004 x=
0 : 0000000000000022
=5B7:  OST-Normal-13:17476=5D Call trace:
=5B7:  OST-Normal-13:17476=5D  __stack_depot_save+0x464/0x46c
=5B7:  OST-Normal-13:17476=5D  kasan_save_stack+0x58/0x70
=5B7:  OST-Normal-13:17476=5D  save_stack_info+0x34/0x138
=5B7:  OST-Normal-13:17476=5D  kasan_save_free_info+0x18/0x24
=5B7:  OST-Normal-13:17476=5D  ____kasan_slab_free+0x16c/0x170
=5B7:  OST-Normal-13:17476=5D  __kasan_slab_free+0x10/0x20
=5B7:  OST-Normal-13:17476=5D  kmem_cache_free+0x238/0x53c
=5B7:  OST-Normal-13:17476=5D  mempool_free_slab+0x1c/0x28
=5B7:  OST-Normal-13:17476=5D  mempool_free+0x7c/0x1a0
=5B7:  OST-Normal-13:17476=5D  sg_pool_free+0x6c/0x84
=5B7:  OST-Normal-13:17476=5D  __sg_free_table+0x88/0xbc
=5B7:  OST-Normal-13:17476=5D  sg_free_table_chained+0x40/0x4c
=5B7:  OST-Normal-13:17476=5D  scsi_free_sgtables+0x3c/0x7c
=5B7:  OST-Normal-13:17476=5D  scsi_mq_uninit_cmd+0x20/0x7c
=5B7:  OST-Normal-13:17476=5D  scsi_end_request+0xd8/0x304
=5B7:  OST-Normal-13:17476=5D  scsi_io_completion+0x88/0x160
=5B7:  OST-Normal-13:17476=5D  scsi_finish_command+0x17c/0x194
=5B7:  OST-Normal-13:17476=5D  scsi_complete+0xcc/0x158
=5B7:  OST-Normal-13:17476=5D  blk_mq_complete_request+0x4c/0x5c
=5B7:  OST-Normal-13:17476=5D  scsi_done_internal+0xf4/0x1e0
=5B7:  OST-Normal-13:17476=5D  scsi_done+0x14/0x20
=5B7:  OST-Normal-13:17476=5D  ufshcd_compl_one_cqe+0x578/0x71c
=5B7:  OST-Normal-13:17476=5D  ufshcd_mcq_poll_cqe_nolock+0xc8/0x150
=5B7:  OST-Normal-13:17476=5D  vendor_mcq_irq+0x74/0x88 =5Bufs-core=5D
=5B7:  OST-Normal-13:17476=5D  __handle_irq_event_percpu+0xd0/0x348
=5B7:  OST-Normal-13:17476=5D  handle_irq_event_percpu+0x24/0x74
=5B7:  OST-Normal-13:17476=5D  handle_irq_event+0x74/0xe0
=5B7:  OST-Normal-13:17476=5D  handle_fasteoi_irq+0x174/0x240
=5B7:  OST-Normal-13:17476=5D  handle_irq_desc+0x7c/0x2c0
=5B7:  OST-Normal-13:17476=5D  generic_handle_domain_irq+0x1c/0x28
=5B7:  OST-Normal-13:17476=5D  gic_handle_irq+0x64/0x158
=5B7:  OST-Normal-13:17476=5D  call_on_irq_stack+0x2c/0x54
=5B7:  OST-Normal-13:17476=5D  do_interrupt_handler+0x70/0xa0
=5B7:  OST-Normal-13:17476=5D  el1_interrupt+0x34/0x68
=5B7:  OST-Normal-13:17476=5D  el1h_64_irq_handler+0x18/0x24
=5B7:  OST-Normal-13:17476=5D  el1h_64_irq+0x68/0x6c
=5B7:  OST-Normal-13:17476=5D  __hwasan_check_x0_67043363+0xc/0x30
=5B7:  OST-Normal-13:17476=5D  ufshcd_queuecommand+0x5f8/0x7b4
=5B7:  OST-Normal-13:17476=5D  scsi_queue_rq+0xb88/0xea4
=5B7:  OST-Normal-13:17476=5D  blk_mq_dispatch_rq_list+0x640/0xe18
=5B7:  OST-Normal-13:17476=5D  blk_mq_do_dispatch_sched+0x47c/0x530
=5B7:  OST-Normal-13:17476=5D  __blk_mq_sched_dispatch_requests+0x158/0x1cc
=5B7:  OST-Normal-13:17476=5D  blk_mq_sched_dispatch_requests+0x68/0x9c
=5B7:  OST-Normal-13:17476=5D  __blk_mq_run_hw_queue+0x9c/0x11c
=5B7:  OST-Normal-13:17476=5D  __blk_mq_delay_run_hw_queue+0xa4/0x234
=5B7:  OST-Normal-13:17476=5D  blk_mq_run_hw_queue+0x130/0x150
=5B7:  OST-Normal-13:17476=5D  blk_mq_sched_insert_requests+0x208/0x3a0
=5B7:  OST-Normal-13:17476=5D  blk_mq_flush_plug_list+0x21c/0x4f0
=5B7:  OST-Normal-13:17476=5D  __blk_flush_plug+0x180/0x1d8
=5B7:  OST-Normal-13:17476=5D  blk_finish_plug+0x40/0x5c
=5B7:  OST-Normal-13:17476=5D  read_pages+0x420/0x4ac
=5B7:  OST-Normal-13:17476=5D  page_cache_ra_unbounded+0xec/0x288
=5B7:  OST-Normal-13:17476=5D  do_page_cache_ra+0x60/0x6c
=5B7:  OST-Normal-13:17476=5D  page_cache_ra_order+0x318/0x364
=5B7:  OST-Normal-13:17476=5D  do_sync_mmap_readahead+0x1a0/0x3c8
=5B7:  OST-Normal-13:17476=5D  filemap_fault+0x260/0x68c
=5B7:  OST-Normal-13:17476=5D  __do_fault+0x80/0x1b4
=5B7:  OST-Normal-13:17476=5D  handle_mm_fault+0x6b4/0x1530
=5B7:  OST-Normal-13:17476=5D  do_page_fault+0x3ec/0x5d4
=5B7:  OST-Normal-13:17476=5D  do_translation_fault+0x44/0x5c
=5B7:  OST-Normal-13:17476=5D  do_mem_abort+0x54/0xd8
=5B7:  OST-Normal-13:17476=5D  el0_ia+0x68/0xf4
=5B7:  OST-Normal-13:17476=5D  el0t_64_sync_handler+0xd0/0x114
=5B7:  OST-Normal-13:17476=5D  el0t_64_sync+0x190/0x194

After analyzing it, it seems that the stack buffer is running out of memory=
,=20
so what do you think about increasing the size of DEPOT_POOLS_CAP to 32768?
Tell us, your opinion

Thanks.