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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id q187sm7297239qka.34.2020.06.08.09.01.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2020 09:01:52 -0700 (PDT) Date: Mon, 8 Jun 2020 12:01:44 -0400 From: Qian Cai To: Peter Zijlstra Cc: Thomas Gleixner , LKML , Andy Lutomirski , Andrew Cooper , X86 ML , "Paul E. McKenney" , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon , Tom Lendacky , Wei Liu , Michael Kelley , Jason Chen CJ , Zhao Yakui Subject: Re: [patch V9 10/39] x86/entry: Provide helpers for execute on irqstack Message-ID: <20200608160144.GA987@lca.pw> References: <20200521200513.656533920@linutronix.de> <20200521202117.763775313@linutronix.de> <20200605171816.GA4259@lca.pw> <20200605173622.GL3976@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200605173622.GL3976@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 05, 2020 at 07:36:22PM +0200, Peter Zijlstra wrote: > On Fri, Jun 05, 2020 at 01:18:16PM -0400, Qian Cai wrote: > > On Thu, May 21, 2020 at 10:05:23PM +0200, Thomas Gleixner wrote: > > > From: Thomas Gleixner > > > > > > Device interrupt handlers and system vector handlers are executed on the > > > interrupt stack. The stack switch happens in the low level assembly entry > > > code. This conflicts with the efforts to consolidate the exit code in C to > > > ensure correctness vs. RCU and tracing. > > > > > > As there is no way to move #DB away from IST due to the MOV SS issue, the > > > requirements vs. #DB and NMI for switching to the interrupt stack do not > > > exist anymore. The only requirement is that interrupts are disabled. > > > > > > That allows to move the stack switching to C code which simplifies the > > > entry/exit handling further because it allows to switch stacks after > > > handling the entry and on exit before handling RCU, return to usermode and > > > kernel preemption in the same way as for regular exceptions. > > > > > > The initial attempt of having the stack switching in inline ASM caused too > > > much headache vs. objtool and the unwinder. After analysing the use cases > > > it was agreed on that having the stack switch in ASM for the price of an > > > indirect call is acceptable as the main users are indirect call heavy > > > anyway and the few system vectors which are empty shells (scheduler IPI and > > > KVM posted interrupt vectors) can run from the regular stack. > > > > > > Provide helper functions to check whether the interrupt stack is already > > > active and whether stack switching is required. > > > > > > 64 bit only for now. 32 bit has a variant of that already. Once this is > > > cleaned up the two implementations might be consolidated as a cleanup on > > > top. > > > > > > Signed-off-by: Thomas Gleixner > > > > Reverted this commit and the rest of series (with trivial fixup) as well > > as the two dependencies [1], > > > > 8449e768dcb8 ("x86/entry: Remove debug IDT frobbing") > > 029149180d1d ("x86/entry: Rename trace_hardirqs_off_prepare()") > > > > fixed the warning under some memory pressure on AMD NUMA servers. > > The warning ? > > > [ 9371.959858] asm_call_on_stack+0x12/0x20 > > asm_call_on_stack at arch/x86/entry/entry_64.S:710 Even after I trimmed the .config [1] to the barely minimal, a subset of LTP test still unable to finish on those AMD servers with page_owner=on. [1]: https://raw.githubusercontent.com/cailca/linux-mm/master/x86.config It looks like because this new IRQ entry introduced by this patch, asm_call_on_stack at arch/x86/entry/entry_64.S:710 handle_edge_irq at kernel/irq/chip.c:832 which will running out of the stack depot limit due to nested loops below. which has this loop, do { ... handle_irq_event(desc); ... } while ((desc->istate & IRQS_PENDING) && !irqd_irq_disabled(&desc->irq_data)); handle_irq_event at kernel/irq/handle.c:215 __handle_irq_event_percpu at kernel/irq/handle.c:156 Here has a nested loop, for_each_action_of_desc(desc, action) { ... res = action->handler(irq, action->dev_id); ... } pqi_irq_handler at drivers/scsi/smartpqi/smartpqi_init.c:3462 pqi_process_io_intr at drivers/scsi/smartpqi/smartpqi_init.c:2992 Here has another nested loop, while (1) { ... io_request->io_complete_callback(io_request, io_request->context); ... } scsi_mq_done at drivers/scsi/scsi_lib.c:1602 blk_mq_complete_request at block/blk-mq.c:677 blk_mq_force_complete_rq at block/blk-mq.c:637 scsi_io_completion at drivers/scsi/scsi_lib.c:934 scsi_end_request at drivers/scsi/scsi_lib.c:584 scsi_mq_uninit_cmd at drivers/scsi/scsi_lib.c:547 scsi_free_sgtables at drivers/scsi/scsi_lib.c:537 __sg_free_table at lib/scatterlist.c:225 Here has one more nested loop, while (table->orig_nents) { ... free_fn(sgl, alloc_size); ... } free_fn() will call kmem_cache_free(). Since we have page_owner=on, it will call save_stack() to save the each free stack trace. > > > > [ 9371.260161] ------------[ cut here ]------------ > > [ 9371.267143] Stack depot reached limit capacity > > [ 9371.267193] WARNING: CPU: 19 PID: 1181 at lib/stackdepot.c:115 stack_depot_save+0x3d9/0x57d > > Is this _the_ warning? > > Maybe it really is running out of storage, I don't think this patch is > to blame. The unwind here looks good, so why would the stack-depot > unwind be any different? > > > [ 9371.281470] Modules linked in: brd vfat fat ext4 crc16 mbcache jbd2 loop kvm_amd kvm ses enclosure dax_pmem irqbypass dax_pmem_core acpi_cpufreq ip_tables x_table > > s xfs sd_mod bnxt_en smartpqi scsi_transport_sas tg3 i40e libphy firmware_class dm_mirror dm_region_hash dm_log dm_mod [last unloaded: dummy_del_mod] > > [ 9371.310176] CPU: 19 PID: 1181 Comm: systemd-journal Tainted: G O 5.7.0-next-20200604+ #1 > > [ 9371.320700] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 03/09/2018 > > [ 9371.329987] RIP: 0010:stack_depot_save+0x3d9/0x57d > > [ 9371.335513] Code: 1d 9b bc 68 01 80 fb 01 0f 87 c0 01 00 00 80 e3 01 75 1f 4c 89 45 c0 c6 05 82 bc 68 01 01 48 c7 c7 e0 85 63 9f e8 9d 74 9d ff <0f> 0b 90 90 4c 8 > > b 45 c0 48 c7 c7 80 1a d0 9f 4c 89 c6 e8 b0 2b 46 > > [ 9371.355426] RSP: 0018:ffffc90007260490 EFLAGS: 00010082 > > [ 9371.361387] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff9ed3207f > > [ 9371.369544] RDX: 0000000000000007 RSI: dffffc0000000000 RDI: 0000000000000000 > > [ 9371.377428] RBP: ffffc900072604f8 R08: fffffbfff3f37539 R09: fffffbfff3f37539 > > [ 9371.385310] R10: ffffffff9f9ba9c3 R11: fffffbfff3f37538 R12: ffffc90007260508 > > [ 9371.393521] R13: 0000000000000036 R14: 0000000000000000 R15: 000000000009fb52 > > [ 9371.401403] FS: 00007fc9849f2980(0000) GS:ffff88942fb80000(0000) knlGS:0000000000000000 > > [ 9371.410244] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 9371.417007] CR2: 00007f20d02c3000 CR3: 0000000440b9c000 CR4: 00000000003406e0 > > [ 9371.424889] Call Trace: > > [ 9371.428054] > > [ 9371.436315] save_stack+0x3f/0x50 > > [ 9371.734034] kasan_slab_free+0xe/0x10 > > [ 9371.738798] slab_free_freelist_hook+0x5d/0x1c0 > > [ 9371.748886] kmem_cache_free+0x10c/0x390 > > [ 9371.758450] mempool_free_slab+0x17/0x20 > > [ 9371.763522] mempool_free+0x65/0x170 > > [ 9371.767825] bio_free+0x14c/0x210 > > [ 9371.771864] bio_put+0x59/0x70 > > [ 9371.775644] end_swap_bio_write+0x199/0x250 > > [ 9371.780556] bio_endio+0x22c/0x4e0 > > [ 9371.784709] dec_pending+0x1bf/0x3e0 [dm_mod] > > [ 9371.790207] clone_endio+0x129/0x3d0 [dm_mod] > > [ 9371.800746] bio_endio+0x22c/0x4e0 > > [ 9371.809262] blk_update_request+0x3bb/0x980 > > [ 9371.814605] scsi_end_request+0x53/0x420 > > [ 9371.824002] scsi_io_completion+0x10a/0x830 > > [ 9371.844445] scsi_finish_command+0x1b9/0x250 > > [ 9371.849445] scsi_softirq_done+0x1ab/0x1f0 > > [ 9371.854272] blk_mq_force_complete_rq+0x217/0x250 > > [ 9371.859708] blk_mq_complete_request+0xe/0x20 > > [ 9371.865171] scsi_mq_done+0xc1/0x220 > > [ 9371.869479] pqi_aio_io_complete+0x83/0x2c0 [smartpqi] > > [ 9371.881764] pqi_irq_handler+0x1fc/0x13f0 [smartpqi] > > [ 9371.914115] __handle_irq_event_percpu+0x81/0x550 > > [ 9371.924289] handle_irq_event_percpu+0x70/0x100 > > [ 9371.945559] handle_irq_event+0x5a/0x8b > > [ 9371.950121] handle_edge_irq+0x10c/0x370 > > [ 9371.950121] handle_edge_irq+0x10c/0x370 > > [ 9371.959858] asm_call_on_stack+0x12/0x20 > > asm_call_on_stack at arch/x86/entry/entry_64.S:710 > > [ 9371.964899] > > [ 9371.967716] common_interrupt+0x185/0x2a0 > > [ 9371.972455] asm_common_interrupt+0x1e/0x40 > > [ 9371.977368] RIP: 0010:__asan_load4+0x8/0xa0 > > [ 9371.982281] Code: 00 e8 5c f4 ff ff 5d c3 40 38 f0 0f 9e c0 84 c0 75 e5 5d c3 48 c1 e8 03 80 3c 10 00 75 ed 5d c3 66 90 55 48 89 e5 48 8b 4d 08 <48> 83 ff fb 77 6c eb 3a 0f 1f 00 48 b8 00 00 00 00 00 00 00 ff 48 > > [ 9372.002246] RSP: 0018:ffffc9000b12f0e8 EFLAGS: 00000202 > > [ 9372.008207] RAX: 0000000000000000 RBX: ffffc9000b12f150 RCX: ffffffff9ed32487 > > [ 9372.016489] RDX: 0000000000000007 RSI: 0000000000000002 RDI: ffffffff9ff92a94 > > [ 9372.024370] RBP: ffffc9000b12f0e8 R08: fffffbfff3ff1d4d R09: fffffbfff3ff1d4d > > [ 9372.032252] R10: ffffffff9ff8ea67 R11: fffffbfff3ff1d4c R12: 0000000000000000 > > [ 9372.040490] R13: ffffc9000b12f358 R14: 000000000000000c R15: 0000000000000005 > > [ 9372.053899] debug_lockdep_rcu_enabled+0x27/0x60 > > [ 9372.059248] rcu_read_lock_held_common+0x12/0x60 > > [ 9372.064989] rcu_read_lock_sched_held+0x60/0xe0 > > [ 9372.080338] shrink_active_list+0xbfd/0xc30 > > [ 9372.120481] shrink_lruvec+0xbf1/0x11b0 > > [ 9372.150410] shrink_node+0x344/0xd10 > > [ 9372.154719] do_try_to_free_pages+0x263/0xa00 > > [ 9372.169860] try_to_free_pages+0x239/0x570 > > [ 9372.179356] __alloc_pages_slowpath.constprop.59+0x5dd/0x1880 > > [ 9372.215762] __alloc_pages_nodemask+0x562/0x670 > > [ 9372.232686] alloc_pages_current+0x9c/0x110 > > [ 9372.237599] alloc_slab_page+0x355/0x530 > > [ 9372.242755] allocate_slab+0x485/0x5a0 > > [ 9372.247232] new_slab+0x46/0x70 > > [ 9372.251095] ___slab_alloc+0x35f/0x810 > > [ 9372.274485] __slab_alloc+0x43/0x70 > > [ 9372.287650] kmem_cache_alloc+0x257/0x3d0 > > [ 9372.298182] prepare_creds+0x26/0x130 > > [ 9372.302571] do_faccessat+0x255/0x3e0 > > [ 9372.321591] __x64_sys_access+0x38/0x40 > > [ 9372.326154] do_syscall_64+0x64/0x340 > > [ 9372.330542] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > [ 9372.336329] RIP: 0033:0x7fc983a21bfb > > [ 9372.341050] Code: Bad RIP value. > > [ 9372.345000] RSP: 002b:00007fffd543cde8 EFLAGS: 00000246 ORIG_RAX: 0000000000000015 > > [ 9372.353319] RAX: ffffffffffffffda RBX: 00007fffd543fa40 RCX: 00007fc983a21bfb > > [ 9372.361199] RDX: 00007fc983cf1c00 RSI: 0000000000000000 RDI: 00005573ed458090 > > [ 9372.369512] RBP: 00007fffd543cf30 R08: 00005573ed44ab99 R09: 0000000000000007 > > [ 9372.377393] R10: 0000000000000041 R11: 0000000000000246 R12: 0000000000000000 > > [ 9372.385275] R13: 0000000000000000 R14: 00007fffd543cea0 R15: 00005573eecd2990 > > [ 9372.393608] irq event stamp: 27274496 > > [ 9372.397999] hardirqs last enabled at (27274495): [] free_unref_page_list+0x2ee/0x400 > > [ 9372.408152] hardirqs last disabled at (27274496): [] idtentry_enter_cond_rcu+0x1b/0x50 > > [ 9372.418695] softirqs last enabled at (27272816): [] __do_softirq+0x478/0x784 > > [ 9372.428154] softirqs last disabled at (27272807): [] irq_exit_rcu+0xd1/0xe0 > > [ 9372.437435] ---[ end trace d2ebac1fad6e452e ]---