[Crash-utility] Re: [PATCH v7 01/15] Fix the regression of cpumask_t for xen hyper
Hi Aditya,
On Wed, Sep 4, 2024 at 10:27 PM Aditya Gupta <adityag(a)linux.ibm.com> wrote:
Hi Tao,
Is this a separate independent patch or related to this series ?
This is an independent patch, but discovered when doing a regression
test against the stack unwinding patchset. Since we have done the
cpumask_t modification in [PATCH v6 10/14], the modification will
continue in v7 as well. So I posted it with v7 together.
Lianbo suggested that I separate some "less strongly connected with
stack unwinding" patches from v7, which formed the part 1 as mentioned
in [1]. Part 1 can be merged prior to the rest of part 2 & 3. So I
think part 1 is also suitable for the cpumask_t regression patch.
[1]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01079.html
Thanks,
Tao Liu
- Aditya Gupta
On 04/09/24 13:19, Tao Liu wrote:
> There is a regression been found for xen hyper due to the commit:
> f615f8fab7bf ("Fix "irq -a" exceeding the memory range issue").
>
> The reason is for xen hyper, kt->cpu is not initialized due to
> kernel_init() won't be called. So 0 would be assigned to cpulen and
> fails the GETBUF().
>
> Before:
> crash> bt -c 2
> bt: zero-size memory allocation! (called from 51f168)
>
> After:
> crash> bt -c 2
> PCPU: 0 VCPU: ffff8300001b8080
> #0 [ffff8300001bfe00] machine_crash_kexec at ffff83000010de72
> #1 [ffff8300001bfe10] do_kexec_op at ffff83000010e3cb
> #2 [ffff8300001bfe50] do_console_io at ffff83000011aff4
> #3 [ffff8300001bfe90] mod_l1_entry at ffff830000129045
> #4 [ffff8300001bfea0] toggle_guest_mode at ffff8300001641bf
> #5 [ffff8300001bfeb0] do_iret at ffff830000164888
> #6 [ffff8300001bff20] syscall_enter at ffff8300001633d2
>
> Since xen hyper will initialize its own cpumask_t, this patch will reuse
> it for XEN_HYPER_MODE. In addition, this patch won't modify the similar
> code hunk in generic_get_irq_affinity(), because for xen, there is no
> "irq" cmd, so the regression won't be triggered.
>
> Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com>
> Cc: Hari Bathini <hbathini(a)linux.ibm.com>
> Cc: Mahesh J Salgaonkar <mahesh(a)linux.ibm.com>
> Cc: Naveen N. Rao <naveen.n.rao(a)linux.vnet.ibm.com>
> Cc: Lianbo Jiang <lijiang(a)redhat.com>
> Cc: HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com>
> Cc: Tao Liu <ltao(a)redhat.com>
> Cc: Alexey Makhalov <alexey.makhalov(a)broadcom.com>
> Cc: Aditya Gupta <adityag(a)linux.ibm.com>
> Signed-off-by: Tao Liu <ltao(a)redhat.com>
> ---
> tools.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/tools.c b/tools.c
> index 2b78b95..dec6e5b 100644
> --- a/tools.c
> +++ b/tools.c
> @@ -16,6 +16,7 @@
> */
>
> #include "defs.h"
> +#include "xen_hyper_defs.h"
> #include <ctype.h>
>
> #ifdef VALGRIND
> @@ -6720,6 +6721,11 @@ get_cpumask_buf(void)
> {
> int cpulen, len_cpumask;
>
> +#ifdef XEN_HYPERVISOR_ARCH
> + if (XEN_HYPER_MODE() && XEN_HYPER_VALID_SIZE(cpumask_t))
> + return (ulong *)GETBUF(XEN_HYPER_SIZE(cpumask_t));
> +#endif
> +
> cpulen = DIV_ROUND_UP(kt->cpus, BITS_PER_LONG) * sizeof(ulong);
> len_cpumask = STRUCT_SIZE("cpumask_t");
> if (len_cpumask > 0)