[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [linux-linus test] 183794: regressions - FAIL
Hi Juergen, On 23/11/2023 05:57, Juergen Gross wrote: 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 norwithout 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 : fffffffffffffffaI am guessing the error was -ENXIO which is returned from map_guest_areain 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 Stefano, are you going to submit the patch formally? 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 SMPFix the issue by using __alloc_percpu and requesting alignment for the memory allocation. Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx> I am guessing we want to backport it. So should this contain a tag to indicate the intention? 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, looking at the x86 code, you seem to use DEFINE_PER_CPU(). So what guarantees that this is not going to cross a page? Cheers, -- Julien Grall
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |