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38232C4CECC; Sat, 30 Nov 2024 03:22:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1732936949; bh=4JxGwtZZdWPpCoP3dRLOQEapfTtkOtXycUEA5b2OO+k=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=keI0BoRCl7KTK+oDSHbpM1vO3HDzTOzekJLQfb/IeXbwK3Kfr8LmqE4GYLI5r/wyy 1XMXVWRHBxCbGo8aV3Ga8OmRZKr7RNO5MuClQQOf/0qSY2yITx0tCcQAuxdzjr+sPR wf1H6O2lKYmW00vqJGCBUsk57Idnp7Z2f8rNX/ts= Date: Fri, 29 Nov 2024 19:22:28 -0800 From: Andrew Morton To: liuye Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mel Gorman , Hugh Dickins , Yang Shi Subject: Re: [PATCH v2 RESEND] mm/vmscan: Fix hard LOCKUP in function isolate_lru_folios Message-Id: <20241129192228.6f08e74a555bedcad71d32f4@linux-foundation.org> In-Reply-To: <20241119060842.274072-1-liuye@kylinos.cn> References: <20240919021443.9170-1-liuye@kylinos.cn> <20241119060842.274072-1-liuye@kylinos.cn> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: 4u4tgfkutezpk771srd7kn77zd6wexxz X-Rspam-User: X-Rspamd-Queue-Id: 9B3AE1C000D X-Rspamd-Server: rspam08 X-HE-Tag: 1732936940-743544 X-HE-Meta: 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 W4tstjgd CccpEdBLmMnkHS2Tte2gZMt9/9UBCkDDTonSgclTWM0rHV/vZhiNOY9gn0KoQsRcjeAncvpezLBLq0B3mpNj73VUURcL1gaS/mFaodC1/ed4FI4HqRSrh27VfVvxtqZ2Y9JSf5uAXJpwMuVt/ofCY6C3wxOyboA1RIeVkLh4Alg9XGPOBZKTzBzeuVJy/S6jwfXuR+oX0Q9frMcZlBUmhAnfLdFFkkZxOovR9NIHbgx53ZTY1twh66BYyH6spjNi6mJGoGnDZHZUhXzpYjBecJ+eRCVCClRge7eNN2Hkhtxjjhaiqq5rVjZ4mCmrmTp0/Fw5B X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 19 Nov 2024 14:08:42 +0800 liuye wrote: > This fixes the following hard lockup in function isolate_lru_folios > when memory reclaim.If the LRU mostly contains ineligible folios > May trigger watchdog. > > watchdog: Watchdog detected hard LOCKUP on cpu 173 > RIP: 0010:native_queued_spin_lock_slowpath+0x255/0x2a0 > Call Trace: > _raw_spin_lock_irqsave+0x31/0x40 > folio_lruvec_lock_irqsave+0x5f/0x90 > folio_batch_move_lru+0x91/0x150 > lru_add_drain_per_cpu+0x1c/0x40 > process_one_work+0x17d/0x350 > worker_thread+0x27b/0x3a0 > kthread+0xe8/0x120 > ret_from_fork+0x34/0x50 > ret_from_fork_asm+0x1b/0x30 > > lruvec->lru_lock owner： > > PID: 2865 TASK: ffff888139214d40 CPU: 40 COMMAND: "kswapd0" > #0 [fffffe0000945e60] crash_nmi_callback at ffffffffa567a555 > #1 [fffffe0000945e68] nmi_handle at ffffffffa563b171 > #2 [fffffe0000945eb0] default_do_nmi at ffffffffa6575920 > #3 [fffffe0000945ed0] exc_nmi at ffffffffa6575af4 > #4 [fffffe0000945ef0] end_repeat_nmi at ffffffffa6601dde > [exception RIP: isolate_lru_folios+403] > RIP: ffffffffa597df53 RSP: ffffc90006fb7c28 RFLAGS: 00000002 > RAX: 0000000000000001 RBX: ffffc90006fb7c60 RCX: ffffea04a2196f88 > RDX: ffffc90006fb7c60 RSI: ffffc90006fb7c60 RDI: ffffea04a2197048 > RBP: ffff88812cbd3010 R8: ffffea04a2197008 R9: 0000000000000001 > R10: 0000000000000000 R11: 0000000000000001 R12: ffffea04a2197008 > R13: ffffea04a2197048 R14: ffffc90006fb7de8 R15: 0000000003e3e937 > ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 > > #5 [ffffc90006fb7c28] isolate_lru_folios at ffffffffa597df53 > #6 [ffffc90006fb7cf8] shrink_active_list at ffffffffa597f788 > #7 [ffffc90006fb7da8] balance_pgdat at ffffffffa5986db0 > #8 [ffffc90006fb7ec0] kswapd at ffffffffa5987354 > #9 [ffffc90006fb7ef8] kthread at ffffffffa5748238 > crash> > > Scenario: > User processe are requesting a large amount of memory and keep page active. > Then a module continuously requests memory from ZONE_DMA32 area. > Memory reclaim will be triggered due to ZONE_DMA32 watermark alarm reached. > However pages in the LRU(active_anon) list are mostly from > the ZONE_NORMAL area. > > Reproduce: > Terminal 1: Construct to continuously increase pages active(anon). > mkdir /tmp/memory > mount -t tmpfs -o size=1024000M tmpfs /tmp/memory > dd if=/dev/zero of=/tmp/memory/block bs=4M > tail /tmp/memory/block > > Terminal 2: > vmstat -a 1 > active will increase. > procs ---memory--- ---swap-- ---io---- -system-- ---cpu--- ... > r b swpd free inact active si so bi bo > 1 0 0 1445623076 45898836 83646008 0 0 0 > 1 0 0 1445623076 43450228 86094616 0 0 0 > 1 0 0 1445623076 41003480 88541364 0 0 0 > 1 0 0 1445623076 38557088 90987756 0 0 0 > 1 0 0 1445623076 36109688 93435156 0 0 0 > 1 0 0 1445619552 33663256 95881632 0 0 0 > 1 0 0 1445619804 31217140 98327792 0 0 0 > 1 0 0 1445619804 28769988 100774944 0 0 0 > 1 0 0 1445619804 26322348 103222584 0 0 0 > 1 0 0 1445619804 23875592 105669340 0 0 0 > > cat /proc/meminfo | head > Active(anon) increase. > MemTotal: 1579941036 kB > MemFree: 1445618500 kB > MemAvailable: 1453013224 kB > Buffers: 6516 kB > Cached: 128653956 kB > SwapCached: 0 kB > Active: 118110812 kB > Inactive: 11436620 kB > Active(anon): 115345744 kB > Inactive(anon): 945292 kB > > When the Active(anon) is 115345744 kB, insmod module triggers > the ZONE_DMA32 watermark. > > perf record -e vmscan:mm_vmscan_lru_isolate -aR > perf script > isolate_mode=0 classzone=1 order=1 nr_requested=32 nr_scanned=2 > nr_skipped=2 nr_taken=0 lru=active_anon > isolate_mode=0 classzone=1 order=1 nr_requested=32 nr_scanned=0 > nr_skipped=0 nr_taken=0 lru=active_anon > isolate_mode=0 classzone=1 order=0 nr_requested=32 nr_scanned=28835844 > nr_skipped=28835844 nr_taken=0 lru=active_anon > isolate_mode=0 classzone=1 order=1 nr_requested=32 nr_scanned=28835844 > nr_skipped=28835844 nr_taken=0 lru=active_anon > isolate_mode=0 classzone=1 order=0 nr_requested=32 nr_scanned=29 > nr_skipped=29 nr_taken=0 lru=active_anon > isolate_mode=0 classzone=1 order=0 nr_requested=32 nr_scanned=0 > nr_skipped=0 nr_taken=0 lru=active_anon > > See nr_scanned=28835844. > 28835844 * 4k = 115343376KB approximately equal to 115345744 kB. > > If increase Active(anon) to 1000G then insmod module triggers > the ZONE_DMA32 watermark. hard lockup will occur. > > In my device nr_scanned = 0000000003e3e937 when hard lockup. > Convert to memory size 0x0000000003e3e937 * 4KB = 261072092 KB. > > [ffffc90006fb7c28] isolate_lru_folios at ffffffffa597df53 > ffffc90006fb7c30: 0000000000000020 0000000000000000 > ffffc90006fb7c40: ffffc90006fb7d40 ffff88812cbd3000 > ffffc90006fb7c50: ffffc90006fb7d30 0000000106fb7de8 > ffffc90006fb7c60: ffffea04a2197008 ffffea0006ed4a48 > ffffc90006fb7c70: 0000000000000000 0000000000000000 > ffffc90006fb7c80: 0000000000000000 0000000000000000 > ffffc90006fb7c90: 0000000000000000 0000000000000000 > ffffc90006fb7ca0: 0000000000000000 0000000003e3e937 > ffffc90006fb7cb0: 0000000000000000 0000000000000000 > ffffc90006fb7cc0: 8d7c0b56b7874b00 ffff88812cbd3000 > > About the Fixes: > Why did it take eight years to be discovered? > > The problem requires the following conditions to occur: > 1. The device memory should be large enough. > 2. Pages in the LRU(active_anon) list are mostly from the ZONE_NORMAL area. > 3. The memory in ZONE_DMA32 needs to reach the watermark. > > If the memory is not large enough, or if the usage design of ZONE_DMA32 > area memory is reasonable, this problem is difficult to detect. > > notes: > The problem is most likely to occur in ZONE_DMA32 and ZONE_NORMAL, > but other suitable scenarios may also trigger the problem. > > Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis") > Thanks. This is old code. I agree on b2e18757f2c9 and thanks for digging that out. I'll add a cc:stable and shall queue it for testing, pending review from others (please). It may be that the -stable tree maintainers ask for a backport of this change into pre-folio-conversion kernels. But given the obscurity of the workload, I'm not sure this would be worth doing. Opinions are sought? > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -223,6 +223,7 @@ enum { > }; > > #define SWAP_CLUSTER_MAX 32UL > +#define SWAP_CLUSTER_MAX_SKIPPED (SWAP_CLUSTER_MAX << 10) > #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX > > /* Bit flag in swap_map */ > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 28ba2b06fc7d..0bdfae413b4c 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1657,6 +1657,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, > unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; > unsigned long skipped = 0; > unsigned long scan, total_scan, nr_pages; > + unsigned long max_nr_skipped = 0; > LIST_HEAD(folios_skipped); > > total_scan = 0; > @@ -1671,9 +1672,12 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan, > nr_pages = folio_nr_pages(folio); > total_scan += nr_pages; > > - if (folio_zonenum(folio) > sc->reclaim_idx) { > + /* Using max_nr_skipped to prevent hard LOCKUP*/ > + if (max_nr_skipped < SWAP_CLUSTER_MAX_SKIPPED && > + (folio_zonenum(folio) > sc->reclaim_idx)) { > nr_skipped[folio_zonenum(folio)] += nr_pages; > move_to = &folios_skipped; > + max_nr_skipped++; > goto move; > } > > -- > 2.25.1