[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [linux-linus test] 183794: regressions - FAIL
On 23.11.23 00:07, Stefano Stabellini wrote: On Wed, 22 Nov 2023, Juergen Gross wrote:On 22.11.23 04:07, Stefano Stabellini wrote:On Mon, 20 Nov 2023, Stefano Stabellini wrote:On Mon, 20 Nov 2023, Juergen Gross wrote:On 20.11.23 03:21, osstest service owner wrote:flight 183794 linux-linus real [real] http://logs.test-lab.xenproject.org/osstest/logs/183794/ Regressions :-( Tests which did not succeed and are blocking, including tests which could not be run: test-arm64-arm64-examine 8 reboot fail REGR. vs. 183766I'm seeing the following in the serial log: Nov 20 00:25:41.586712 [ 0.567318] kernel BUG at arch/arm64/xen/../../arm/xen/enlighten.c:164! Nov 20 00:25:41.598711 [ 0.574002] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP The related source code lines in the kernel are: ········err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu), ································ &info); ········BUG_ON(err); I suspect commit 20f3b8eafe0ba to be the culprit. Stefano, could you please have a look?The good news and bad news is that I cannot repro this neither with nor without CONFIG_UNMAP_KERNEL_AT_EL0. I looked at commit 20f3b8eafe0ba but I cannot see anything wrong with it. Looking at the register dump, from: x0 : fffffffffffffffa I am guessing the error was -ENXIO which is returned from map_guest_area in Xen. Could it be that the struct is crossing a page boundary? Or that it is not 64-bit aligned? Do we need to do something like the following? diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 9afdc4c4a5dc..5326070c5dc0 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -484,7 +485,7 @@ static int __init xen_guest_init(void) * for secondary CPUs as they are brought up. * For uniformity we use VCPUOP_register_vcpu_info even on cpu0. */ - xen_vcpu_info = alloc_percpu(struct vcpu_info); + xen_vcpu_info = __alloc_percpu(struct vcpu_info, PAGE_SIZE); if (xen_vcpu_info == NULL) return -ENOMEM;May I suggest to use a smaller alignment? What about: 1 << fls(sizeof(struct vcpu_info) - 1)See below --- [PATCH] arm/xen: fix xen_vcpu_info allocation alignment xen_vcpu_info is a percpu area than needs to be mapped by Xen. Currently, it could cross a page boundary resulting in Xen being unable to map it: [ 0.567318] kernel BUG at arch/arm64/xen/../../arm/xen/enlighten.c:164! [ 0.574002] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Fix the issue by using __alloc_percpu and requesting alignment for the memory allocation. Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 9afdc4c4a5dc..09eb74a07dfc 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -484,7 +484,8 @@ static int __init xen_guest_init(void) * for secondary CPUs as they are brought up. * For uniformity we use VCPUOP_register_vcpu_info even on cpu0. */ - xen_vcpu_info = alloc_percpu(struct vcpu_info); + xen_vcpu_info = __alloc_percpu(sizeof(struct vcpu_info), + 1 << fls(sizeof(struct vcpu_info) - 1)); Nit: one tab less, please (can be fixed while committing). if (xen_vcpu_info == NULL) return -ENOMEM; Reviewed-by: Juergen Gross <jgross@xxxxxxxx> Juergen Attachment:
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