Re: [Crash-utility] [PATCH]: nr_node_ids

On Fri, Sep 7, 2012 at 4:28 PM, Dave Anderson <anderson(a)redhat.com&gt; wrote: > > > ----- Original Message ----- >> Hi all, >> >> I'm wondering about the use of the kernel 'nr_node_ids' variable in >> memory.c. In kmem_cache_downsize(), vt->kmem_cache_len_nodes defaults >> to 1 when 'nr_node_ids' isn't present. But in vm_init() an error >> message is printed in the same case. The reason I'm asking is that I'm >> getting that error >> >> "unable to initialize kmem slab cache subsystem" >> >> on a 3.4 kernel. Having vm_init() default to >> >> vt->kmem_cache_len_nodes=1 >> >> as well seems to bring up the slab subsystem, although I'm getting a >> couple of >> >> "kmem: vm_area_struct: full list: slab: <nn1> bad next pointer: <nn2>" >> >> mixed into my kmem -S output. I have no idea if it's related. > > Hi Per, Hello =o) > > I don't have any recent sample kernels that have the configuration that your > kernel is running, so I can't confidently answer/test this. I presume that > your kernel does not configure CONFIG_NODES_SHIFT (or set it to 0), so > that nr_node_ids becomes a #define instead of a variable. And to get it Indeed, that's exactly what happened. > to work, I'm also presuming that you changed the "else" clause in vm_init() > to something like this: > > if (MEMBER_TYPE("kmem_cache", "nodelists") == TYPE_CODE_PTR) { > int nr_node_ids; > /* > * nodelists now a pointer to an outside array > */ > vt->flags |= NODELISTS_IS_PTR; > if (kernel_symbol_exists("nr_node_ids")) { > get_symbol_data("nr_node_ids", sizeof(int), > &nr_node_ids); > vt->kmem_cache_len_nodes = nr_node_ids; > } else { > - error(INFO, "nr_node_ids: symbol does not exist\n"); > - error(INFO, "unable to initialize kmem slab cache subsystem\n\n"); > - vt->flags |= KMEM_CACHE_UNAVAIL; > + vt->kmem_cache_len_nodes = 1; > } Again, indeed, that's more or less to the character what I changed it to. > > That looks reasonable to me. > Ok, because that was the main purpose of my first mail, understanding whether there was a reason why the 'nr_node_ids'-has-been-turned-into-a-macro-case was treated as an error in this context. So, you agree we could change it?

> As far as the "kmem -S" output, are you running it on a live system? > Nope, dead as a doornail. Are these messages to be expected then?

Oh, and sorry for putting "[PATCH]" in the title when there wasn't one. It was by accident. /Per