[Crash-utility] Re: [PATCH] memory: Handle crash failure in linux-next caused by struct kmem_cache changes

Hi Mikhail, Thanks for your fix on this! On Tue, Jan 27, 2026 at 8:40 PM Mikhail Zaslonko <zaslonko(a)linux.ibm.com&gt; wrote: > > Since kernel commit cf338283652f ("slab: remove struct kmem_cache_cpu") > in linux-next we have no more 'cpu_slab' member in struct kmem_cache. > Pick 'cpu_sheaves' as an alternative kmem_cache member for kernel-next to > identify the SLUB case. > > Without the patch, crash fails to start on kernel-next with the error > message: > > crash: invalid structure member offset: kmem_cache_s_num > FILE: memory.c LINE: 9988 FUNCTION: kmem_cache_init() > > This fix allows the crash to start with no errors. But kmap -s is no > longer working for kernel-next since kmem_cache_cpu array is completely > missing. > > Signed-off-by: Mikhail Zaslonko <zaslonko(a)linux.ibm.com&gt; > --- > memory.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/memory.c b/memory.c > index cbc8d2f..3373fdb 100644 > --- a/memory.c > +++ b/memory.c > @@ -672,6 +672,7 @@ vm_init(void) > } else if (!VALID_STRUCT(kmem_slab_s) && > !VALID_STRUCT(slab_s) && > !MEMBER_EXISTS("kmem_cache", "cpu_slab") && > + !MEMBER_EXISTS("kmem_cache", "cpu_sheaves") && > (VALID_STRUCT(slab) || (vt->flags & SLAB_OVERLOAD_PAGE))) { > vt->flags |= PERCPU_KMALLOC_V2; > > @@ -816,7 +817,7 @@ vm_init(void) > if (INVALID_MEMBER(page_first_page)) > ANON_MEMBER_OFFSET_INIT(page_first_page, "page", "first_page"); > > - } else if (MEMBER_EXISTS("kmem_cache", "cpu_slab") && > + } else if ((MEMBER_EXISTS("kmem_cache", "cpu_slab") || MEMBER_EXISTS("kmem_cache", "cpu_sheaves")) && > STRUCT_EXISTS("kmem_cache_node")) { > vt->flags |= KMALLOC_SLUB; > I tested your patch and find "kmem -s/-S" both not work: crash> kmem -s CACHE OBJSIZE ALLOCATED TOTAL SLABS SSIZE NAME kmem: cannot determine location of kmem_cache.cpu_slab page crash> kmem -S CACHE OBJSIZE ALLOCATED TOTAL SLABS SSIZE NAME kmem: cannot determine location of kmem_cache.cpu_slab page And I add the following change upon your patch, to 1) let "kmem -s" work and 2) "kmem -S" output error info. @@ -5270,6 +5272,9 @@ cmd_kmem(void) if (sflag || Sflag || rflag || !(vt->flags & KMEM_CACHE_INIT)) kmem_cache_init(); + if (Sflag && MEMBER_EXISTS("kmem_cache", "cpu_sheaves")) + error(FATAL, "-S not supported for this kernel\n"); +

while (args[optind]) { if (hexadecimal(args[optind], 0)) { value[spec_addr++] = @@ -20401,7 +20406,6 @@ get_cpu_slab_ptr(struct meminfo *si, int cpu, ulong *cpu_freelist) default: cpu_slab_ptr = 0; - error(FATAL, "cannot determine location of

Thanks, Tao Liu > -- > 2.52.0 >