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Message-ID: <ce9cb3c5-be63-45f0-91ad-4f7ab335d3b2@redhat.com>
Date: Tue, 18 Jun 2024 15:08:02 +0200
From: David Hildenbrand <david@...hat.com>
To: Chris Li <chrisl@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>
Cc: Kairui Song <kasong@...cent.com>, Ryan Roberts <ryan.roberts@....com>,
"Huang, Ying" <ying.huang@...el.com>, Kalesh Singh <kaleshsingh@...gle.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Barry Song <baohua@...nel.org>
Subject: Re: [PATCH v2 0/2] mm: swap: mTHP swap allocator base on swap cluster
order
On 15.06.24 01:48, Chris Li wrote:
> This is the short term solutiolns "swap cluster order" listed
> in my "Swap Abstraction" discussion slice 8 in the recent
> LSF/MM conference.
>
> When commit 845982eb264bc "mm: swap: allow storage of all mTHP
> orders" is introduced, it only allocates the mTHP swap entries
> from new empty cluster list. It has a fragmentation issue
> reported by Barry.
>
> https://lore.kernel.org/all/CAGsJ_4zAcJkuW016Cfi6wicRr8N9X+GJJhgMQdSMp+Ah+NSgNQ@mail.gmail.com/
>
> The mTHP allocation failure rate raises to almost 100% after a few
> hours in Barry's test run.
>
> The reason is that all the empty cluster has been exhausted while
> there are planty of free swap entries to in the cluster that is
> not 100% free.
>
> Remember the swap allocation order in the cluster.
> Keep track of the per order non full cluster list for later allocation.
>
> This greatly improve the sucess rate of the mTHP swap allocation.
>
> There is some test number in the V1 thread of this series:
> https://lore.kernel.org/r/20240524-swap-allocator-v1-0-47861b423b26@kernel.org
>
> Reported-by: Barry Song <21cnbao@...il.com>
> Signed-off-by: Chris Li <chrisl@...nel.org>
> ---
Running the cow.c selftest with a bunch of debug config
settings enabled, I get on mm-unstable:
[ 25.236555] list_add corruption. prev->next should be next (ffff888105b5ad08), but was ffff888105b5ae78. (prev=ffff88812580b048).
[ 25.237432] ------------[ cut here ]------------
[ 25.237702] kernel BUG at lib/list_debug.c:32!
[ 25.237962] Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 25.238288] CPU: 23 PID: 1264 Comm: cow Tainted: G W 6.10.0-rc4+ #301
[ 25.238720] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 25.239335] RIP: 0010:__list_add_valid_or_report+0x78/0xa0
[ 25.239646] Code: 6b ff 0f 0b 48 89 c1 48 c7 c7 c0 30 0e 83 e8 7f e5 6b ff 0f 0b 48 89 d1 48 89 c6 4c 89 c2 48 c7 c7 18 31 0e 83 e8 68 e5 6b ff <0f> 0b 48 89 f2 48 89 c1 48 89 fe 48 c7 c7 70 31 0e 83 e8 51 e5b
[ 25.240670] RSP: 0000:ffffc90002c87bd0 EFLAGS: 00010246
[ 25.240964] RAX: 0000000000000075 RBX: ffff888105b5ac00 RCX: 0000000000000000
[ 25.241362] RDX: 0000000000000000 RSI: ffff88885f9a1a00 RDI: ffff88885f9a1a00
[ 25.241762] RBP: ffff88810624de20 R08: 0000000000000000 R09: 0000000000000003
[ 25.242158] R10: ffffc90002c87a78 R11: ffffffff83b5b808 R12: 0000000000044000
[ 25.242556] R13: 0000000000044000 R14: ffff88810624e000 R15: ffff88812580bb00
[ 25.242960] FS: 00007f4fb364b740(0000) GS:ffff88885f980000(0000) knlGS:0000000000000000
[ 25.243413] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 25.243737] CR2: 00007f4fb343c000 CR3: 000000010a5dc000 CR4: 0000000000750ef0
[ 25.244145] PKRU: 55555554
[ 25.244303] Call Trace:
[ 25.244445] <TASK>
[ 25.244572] ? die+0x36/0x90
[ 25.244742] ? do_trap+0xdd/0x100
[ 25.244935] ? __list_add_valid_or_report+0x78/0xa0
[ 25.245211] ? __list_add_valid_or_report+0x78/0xa0
[ 25.245488] ? do_error_trap+0x81/0x110
[ 25.245710] ? __list_add_valid_or_report+0x78/0xa0
[ 25.245988] ? exc_invalid_op+0x50/0x70
[ 25.246211] ? __list_add_valid_or_report+0x78/0xa0
[ 25.246488] ? asm_exc_invalid_op+0x1a/0x20
[ 25.246737] ? __list_add_valid_or_report+0x78/0xa0
[ 25.247016] swapcache_free_entries+0x1ec/0x240
[ 25.247286] free_swap_slot+0xcc/0xe0
[ 25.247498] put_swap_folio+0xf3/0x3b0
[ 25.247720] delete_from_swap_cache+0x68/0x90
[ 25.247972] folio_free_swap+0xd0/0x200
[ 25.248201] do_swap_page+0xd95/0x12d0
[ 25.248418] ? __entry_text_end+0x101e45/0x101e49
[ 25.248695] ? srso_alias_return_thunk+0x5/0xfbef5
[ 25.248969] ? srso_alias_return_thunk+0x5/0xfbef5
[ 25.249246] ? __pte_offset_map+0x18e/0x270
[ 25.249490] __handle_mm_fault+0x915/0xf80
[ 25.249731] ? srso_alias_return_thunk+0x5/0xfbef5
[ 25.250010] handle_mm_fault+0x1d1/0x400
[ 25.250242] do_user_addr_fault+0x16f/0x790
[ 25.250485] exc_page_fault+0x83/0x260
[ 25.250706] asm_exc_page_fault+0x26/0x30
Maybe what Hugh reported already. I'll try reverting your patches
to see if that fixes these issues.
--
Cheers,
David / dhildenb
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