[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] BUG: using smp_processor_id() in preemptible [00000000] code: blkback.1.xvdb/9138 caller is decrease_reservation
Wednesday, September 11, 2013, 6:25:35 PM, you wrote: > Wednesday, September 11, 2013, 2:39:01 PM, you wrote: >> On 11/09/13 13:08, Stefano Stabellini wrote: >>> On Wed, 11 Sep 2013, David Vrabel wrote: >>>> On 10/09/13 19:13, Sander Eikelenboom wrote: >>>>> Hi Wei, >>>>> >>>>> Just back from holiday i tried running a new xen-unstable and >>>>> linux kernel (current Linus his tree + Konrad's last pull request >>>>> merged on top). I saw a thread and patch about a bug_on in >>>>> increase_reservation ... i'm seeing the splat below in dom0 when >>>>> guests get started. >>>> >>>> Yes, the use of __per_cpu() in decrease_reservation is not safe. >>>> >>>> Stefano, what testing did you give "xen/balloon: set a mapping for >>>> ballooned out pages" (cd9151e2). The number of critical problems >>>> it's had suggests not a lot? >>>> >>>> I'm also becoming less happy with the inconsistency between the >>>> p2m updates between the different (non-)auto_translated_physmap >>>> guest types. >>>> >>>> I think it (and all the attempts to fix it) should be reverted at >>>> this stage and we should try again for 3.13 which some more through >>>> testing and a more careful look at what updates to the p2m are >>>> needed. >>> >>> Issues like this one are due to different kernel configurations / >>> usage patters. To reproduce this issue one needs a preemptible kernel >>> and blkback. I use a non-preemptible kernel and QEMU as block >>> backend. >>> >>> Granted, in this case I should have tested blkback and both >>> preemptible and non-preemptible kernel configurations. But in >>> general it is nearly impossible to test all the possible >>> configurations beforehand, it is a classic case of combinatorial >>> explosion. >>> >>> These are exactly the kind of things that an exposure to a wider >>> range of users/developers help identify and fix. >>> >>> So I think that we did the right thing here, by sending a pull >>> request early in the release cycle, so that now we have many other >>> RCs to fix all the issues that come up. >> That sounds fair. >> Sander, does the follow patch fix this issue? > Hi David, > This patch indeed seems to fix it. Spoke too soon, starting a guest is fixed now, shutting it down oopses: [ 910.980798] vpn_bridge: port 1(vif13.0) entered disabled state [ 910.988352] vpn_bridge: port 1(vif13.0) entered disabled state [ 910.995427] device vif13.0 left promiscuous mode [ 911.001821] vpn_bridge: port 1(vif13.0) entered disabled state [ 911.364617] ------------[ cut here ]------------ [ 911.371022] kernel BUG at drivers/xen/balloon.c:365! [ 911.377395] invalid opcode: 0000 [#1] PREEMPT SMP [ 911.383775] Modules linked in: [ 911.390099] CPU: 4 PID: 16626 Comm: kworker/4:2 Not tainted 3.11.0-mw-20130911-notl-balloonfix #1 [ 911.396620] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS V1.8B1 09/13/2010 [ 911.403172] Workqueue: events balloon_process [ 911.409724] task: ffff88004eef2120 ti: ffff88004d44a000 task.ti: ffff88004d44a000 [ 911.416321] RIP: e030:[<ffffffff814a7264>] [<ffffffff814a7264>] balloon_process+0x2f4/0x300 [ 911.423168] RSP: e02b:ffff88004d44bd08 EFLAGS: 00010207 [ 911.430016] RAX: 00000000005462f6 RBX: 0000000000000000 RCX: 0000000000000001 [ 911.436980] RDX: ffffffff82d67000 RSI: 00000000000001b3 RDI: 000000000004b5b3 [ 911.444011] RBP: ffff88004d44bd68 R08: 0000000000000000 R09: ffff88004eef2840 [ 911.450898] R10: 0000000000000000 R11: 0000000000000001 R12: 0000160000000000 [ 911.457625] R13: 0000000000000001 R14: ffffea00012d6cc0 R15: 000000000004b5b3 [ 911.464405] FS: 00007fdfbfd58700(0000) GS:ffff88005f700000(0000) knlGS:0000000000000000 [ 911.471219] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b [ 911.478082] CR2: 00007f2bc3fdaf30 CR3: 0000000050ac9000 CR4: 0000000000000660 [ 911.485030] Stack: [ 911.491763] 0000000000000000 0000000000000001 ffffffff82d31900 0000000000000001 [ 911.498705] 0000000000000000 0000000000007ff0 ffff880000000000 ffffffff82266d00 [ 911.505751] ffff88005f712c80 ffff88005f717000 0000000000000000 ffff88004f693080 [ 911.512803] Call Trace: [ 911.519802] [<ffffffff810b0e1d>] process_one_work+0x1bd/0x430 [ 911.526905] [<ffffffff810b0db7>] ? process_one_work+0x157/0x430 [ 911.533975] [<ffffffff810b2012>] worker_thread+0x112/0x360 [ 911.540988] [<ffffffff810b1f00>] ? manage_workers.isra.23+0x290/0x290 [ 911.547921] [<ffffffff810b8c86>] kthread+0xd6/0xe0 [ 911.554787] [<ffffffff81a4a23b>] ? _raw_spin_unlock_irq+0x2b/0x70 [ 911.561854] [<ffffffff810b8bb0>] ? __init_kthread_worker+0x70/0x70 [ 911.568932] [<ffffffff81a4b2bc>] ret_from_fork+0x7c/0xb0 [ 911.575955] [<ffffffff810b8bb0>] ? __init_kthread_worker+0x70/0x70 [ 911.582948] Code: 6d 26 82 bf 08 00 00 00 e8 aa 91 c0 ff eb 9b 31 c9 e9 61 fe ff ff 0f 0b 0f 0b 4c 89 ff e8 35 2e b6 ff 48 ff c0 0f 84 9c fe ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 41 89 d7 [ 911.597747] RIP [<ffffffff814a7264>] balloon_process+0x2f4/0x300 [ 911.605129] RSP <ffff88004d44bd08> [ 911.612506] ---[ end trace 04f1bc1297ee6627 ]--- [ 911.619911] BUG: unable to handle kernel paging request at ffffffffffffffa8 [ 911.627457] IP: [<ffffffff810b8f4b>] kthread_data+0xb/0x20 [ 911.635063] PGD 220f067 PUD 2211067 PMD 0 [ 911.642664] Oops: 0000 [#2] PREEMPT SMP [ 911.650087] Modules linked in: [ 911.657394] CPU: 4 PID: 16626 Comm: kworker/4:2 Tainted: G D 3.11.0-mw-20130911-notl-balloonfix #1 [ 911.664959] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640) , BIOS V1.8B1 09/13/2010 [ 911.672722] task: ffff88004eef2120 ti: ffff88004d44a000 task.ti: ffff88004d44a000 [ 911.680547] RIP: e030:[<ffffffff810b8f4b>] [<ffffffff810b8f4b>] kthread_data+0xb/0x20 [ 911.688475] RSP: e02b:ffff88004d44b8e8 EFLAGS: 00010092 [ 911.696220] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000000000f [ 911.704218] RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88004eef2120 [ 911.712222] RBP: ffff88004d44b8e8 R08: ffff88004eef21b0 R09: 0000000000000165 [ 911.720089] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88004eef2510 [ 911.727639] R13: 0000000000000004 R14: ffff88004eef2110 R15: ffff88004eef2120 [ 911.735015] FS: 00007f68eb707700(0000) GS:ffff88005f700000(0000) knlGS:0000000000000000 [ 911.742459] CS: e033 DS: 0000 ES: 0000 CR0: 000000008005003b [ 911.749743] CR2: 0000000000000028 CR3: 0000000047295000 CR4: 0000000000000660 [ 911.756818] Stack: [ 911.763909] ffff88004d44b908 ffffffff810b25e0 ffff88004d44b908 ffff88005f713700 [ 911.771115] ffff88004d44ba38 ffffffff81a48237 ffff88004d44b938 ffffffff8111b1bc [ 911.778316] ffff88004eef2120 ffff88004d44bfd8 ffff88004d44bfd8 ffff88004d44bfd8 [ 911.785588] Call Trace: [ 911.792734] [<ffffffff810b25e0>] wq_worker_sleeping+0x10/0x90 [ 911.799936] [<ffffffff81a48237>] __schedule+0x647/0x8e0 [ 911.807193] [<ffffffff8111b1bc>] ? rcu_is_cpu_idle+0x3c/0x60 [ 911.814320] [<ffffffff814157f6>] ? debug_smp_processor_id+0x56/0x100 [ 911.821352] [<ffffffff81090203>] ? __serpent_dec_blk8_avx+0x91b/0x3cc8 [ 911.828385] [<ffffffff810e989c>] ? lock_acquire+0xdc/0x100 [ 911.835244] [<ffffffff8109ad03>] ? do_exit+0x5d3/0xa20 [ 911.842019] [<ffffffff8111d582>] ? call_rcu+0x12/0x20 [ 911.848682] [<ffffffff810e96a3>] ? lock_release+0x133/0x250 [ 911.855278] [<ffffffff81a485f4>] schedule+0x24/0x60 [ 911.861884] [<ffffffff8109add2>] do_exit+0x6a2/0xa20 [ 911.868489] [<ffffffff810e96a3>] ? lock_release+0x133/0x250 [ 911.875031] [<ffffffff810114f6>] oops_end+0xa6/0xf0 [ 911.881646] [<ffffffff81011693>] die+0x53/0x80 [ 911.888163] [<ffffffff8100df79>] do_trap+0x69/0x160 [ 911.894532] [<ffffffff8100e292>] ? do_invalid_op+0x72/0xc0 [ 911.900945] [<ffffffff8100e2c6>] do_invalid_op+0xa6/0xc0 [ 911.907225] [<ffffffff814a7264>] ? balloon_process+0x2f4/0x300 [ 911.913448] [<ffffffff810e391f>] ? trace_hardirqs_off_caller+0x8f/0x160 [ 911.919774] [<ffffffff8140debd>] ? trace_hardirqs_off_thunk+0x3a/0x3c [ 911.926001] [<ffffffff81a4aa67>] ? restore_args+0x30/0x30 [ 911.932120] [<ffffffff81a4c5ae>] invalid_op+0x1e/0x30 [ 911.938231] [<ffffffff814a7264>] ? balloon_process+0x2f4/0x300 [ 911.944381] [<ffffffff814a725b>] ? balloon_process+0x2eb/0x300 [ 911.950474] [<ffffffff810b0e1d>] process_one_work+0x1bd/0x430 [ 911.956583] [<ffffffff810b0db7>] ? process_one_work+0x157/0x430 [ 911.962660] [<ffffffff810b2012>] worker_thread+0x112/0x360 [ 911.968630] [<ffffffff810b1f00>] ? manage_workers.isra.23+0x290/0x290 [ 911.974632] [<ffffffff810b8c86>] kthread+0xd6/0xe0 [ 911.980656] [<ffffffff81a4a23b>] ? _raw_spin_unlock_irq+0x2b/0x70 [ 911.986807] [<ffffffff810b8bb0>] ? __init_kthread_worker+0x70/0x70 [ 911.992676] [<ffffffff81a4b2bc>] ret_from_fork+0x7c/0xb0 [ 911.998346] [<ffffffff810b8bb0>] ? __init_kthread_worker+0x70/0x70 [ 912.004019] Code: 00 48 89 e5 5d 48 8b 40 98 48 c1 e8 02 83 e0 01 c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 48 8b 87 98 03 00 00 55 48 89 e5 <48> 8b 40 a8 5d c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 [ 912.016141] RIP [<ffffffff810b8f4b>] kthread_data+0xb/0x20 [ 912.022115] RSP <ffff88004d44b8e8> [ 912.027951] CR2: ffffffffffffffa8 [ 912.033744] ---[ end trace 04f1bc1297ee6628 ]--- [ 912.039588] Fixing recursive fault but reboot is needed! > Thx, > Sander >> 8<--------------------------------------------------- >> xen/balloon: ensure preemption is disabled when using a scratch page >> In decrease_reservation(), if the kernel is preempted between updating >> the mapping and updating the p2m then they may end up using different >> scratch pages. >> Use get_balloon_scratch_page() and put_balloon_scratch_page() which use >> get_cpu_var() and put_cpu_var() to correctly disable preemption. >> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx> >> --- >> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c >> index 3101cf6..a74647b 100644 >> --- a/drivers/xen/balloon.c >> +++ b/drivers/xen/balloon.c >> @@ -305,6 +305,18 @@ static enum bp_state reserve_additional_memory(long >> credit) >> } >> #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ >> >> +struct page *get_balloon_scratch_page(void) >> +{ >> + struct page *ret = get_cpu_var(balloon_scratch_page); >> + BUG_ON(ret == NULL); >> + return ret; >> +} >> + >> +void put_balloon_scratch_page(void) >> +{ >> + put_cpu_var(balloon_scratch_page); >> +} >> + >> static enum bp_state increase_reservation(unsigned long nr_pages) >> { >> int rc; >> @@ -380,6 +392,7 @@ static enum bp_state decrease_reservation(unsigned long >> nr_pages, gfp_t gfp) >> enum bp_state state = BP_DONE; >> unsigned long pfn, i; >> struct page *page; >> + struct page *scratch_page; >> int ret; >> struct xen_memory_reservation reservation = { >> .address_bits = 0, >> @@ -399,6 +412,8 @@ static enum bp_state decrease_reservation(unsigned long >> nr_pages, gfp_t gfp) >> if (nr_pages > ARRAY_SIZE(frame_list)) >> nr_pages = ARRAY_SIZE(frame_list); >> >> + scratch_page = get_balloon_scratch_page(); >> + >> for (i = 0; i < nr_pages; i++) { >> page = alloc_page(gfp); >> if (page == NULL) { >> @@ -416,7 +431,7 @@ static enum bp_state decrease_reservation(unsigned long >> nr_pages, gfp_t gfp) >> if (xen_pv_domain() && !PageHighMem(page)) { >> ret = HYPERVISOR_update_va_mapping( >> (unsigned long)__va(pfn << PAGE_SHIFT), >> - >> pfn_pte(page_to_pfn(__get_cpu_var(balloon_scratch_page)), >> + pfn_pte(page_to_pfn(scratch_page), >> PAGE_KERNEL_RO), 0); >> BUG_ON(ret); >> } >> @@ -432,14 +447,14 @@ static enum bp_state decrease_reservation(unsigned >> long nr_pages, gfp_t gfp) >> pfn = mfn_to_pfn(frame_list[i]); >> if (!xen_feature(XENFEAT_auto_translated_physmap)) { >> unsigned long p; >> - struct page *pg; >> - pg = __get_cpu_var(balloon_scratch_page); >> - p = page_to_pfn(pg); >> + p = page_to_pfn(scratch_page); >> __set_phys_to_machine(pfn, pfn_to_mfn(p)); >> } >> balloon_append(pfn_to_page(pfn)); >> } >> >> + put_balloon_scratch_page(); >> + >> set_xen_guest_handle(reservation.extent_start, frame_list); >> reservation.nr_extents = nr_pages; >> ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, >> &reservation); >> @@ -491,18 +506,6 @@ static void balloon_process(struct work_struct *work) >> mutex_unlock(&balloon_mutex); >> } >> >> -struct page *get_balloon_scratch_page(void) >> -{ >> - struct page *ret = get_cpu_var(balloon_scratch_page); >> - BUG_ON(ret == NULL); >> - return ret; >> -} >> - >> -void put_balloon_scratch_page(void) >> -{ >> - put_cpu_var(balloon_scratch_page); >> -} >> - >> /* Resets the Xen limit, sets new target, and kicks off processing. */ >> void balloon_set_new_target(unsigned long target) >> { _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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