----- "Tejun Heo" <tj at kernel.org> wrote:
> Hello,
>
> I was slightly confused with the debug patch but it looks like
> someone
> is feeding non-percpu address to the function. Hmm... or it could be
> that the first chunk test is returning false incorrectly for an
> address which is inside static percpu area. Can you please try the
> following patch instead? This should make the problem go away and
> give us enough information about which address is causing the
> problem.
> Please attach logs from both the original kernel before triggering
> crash and from the crash kernel.
I can't reproduce it anymore after applied the patch. Both the first and the second kernel logs attached.
>
> Thank you.
>
> diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
> index 7d9c1d0..357569a 100644
> --- a/mm/percpu-vm.c
> +++ b/mm/percpu-vm.c
> @@ -415,6 +415,7 @@ static struct pcpu_chunk *pcpu_create_chunk(void)
> {
> struct pcpu_chunk *chunk;
> struct vm_struct **vms;
> + int i;
>
> chunk = pcpu_alloc_chunk();
> if (!chunk)
> @@ -429,6 +430,13 @@ static struct pcpu_chunk
> *pcpu_create_chunk(void)
>
> chunk->data = vms;
> chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
> + chunk->chunkno = ++chunkno;
> + printk("XXX chunk %d allocated base_addr=%p\n",
> + chunk->chunkno, chunk->base_addr);
> + printk("XXX VMS:");
> + for (i = 0; i < pcpu_nr_groups; i++)
> + printk(" %zu@%p", vms[i]->size, vms[i]->addr);
> + printk("\n");
> return chunk;
> }
>
> diff --git a/mm/percpu.c b/mm/percpu.c
> index 77e3f5a..14c836b 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -96,7 +96,10 @@
> #define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
> #endif /* CONFIG_SMP */
>
> +static int chunkno;
> +
> struct pcpu_chunk {
> + int chunkno;
> struct list_head list; /* linked to pcpu_slot lists */
> int free_size; /* free bytes in the chunk */
> int contig_hint; /* max contiguous size hint */
> @@ -182,6 +185,40 @@ static struct list_head *pcpu_slot __read_mostly;
> /* chunk list slots */
> static void pcpu_reclaim(struct work_struct *work);
> static DECLARE_WORK(pcpu_reclaim_work, pcpu_reclaim);
>
> +void pcpu_dump_chunk(struct pcpu_chunk *chunk)
> +{
> + int i, contig = 0, free = 0;
> +
> + printk("XXX %d(f=%d,c=%d,u=%d,a=%d)", chunk->chunkno,
> + chunk->free_size, chunk->contig_hint,
> + chunk->map_used, chunk->map_alloc);
> + for (i = 0; i < chunk->map_used; i++) {
> + if (chunk->map[i] > 0) {
> + free += chunk->map[i];
> + contig = max(contig, chunk->map[i]);
> + }
> + printk(" %d", chunk->map[i]);
> + }
> + printk(" free=%d contig=%d%s\n", free, contig,
> + (free != chunk->free_size || contig != chunk->contig_hint) ?
> + " MISMATCH!" : "");
> +}
> +
> +void pcpu_dump_chunk_slots(void)
> +{
> + struct pcpu_chunk *chunk;
> + int i;
> +
> + printk("XXX percpu allocator dump\n");
> + for (i = 0; i < pcpu_nr_slots; i++) {
> + if (list_empty(&pcpu_slot[i]))
> + continue;
> + printk("XXX SLOT[%02d]\n", i);
> + list_for_each_entry(chunk, &pcpu_slot[i], list)
> + pcpu_dump_chunk(chunk);
> + }
> +}
> +
> static bool pcpu_addr_in_first_chunk(void *addr)
> {
> void *first_start = pcpu_first_chunk->base_addr;
> @@ -1017,8 +1054,20 @@ phys_addr_t per_cpu_ptr_to_phys(void *addr)
> return __pa(addr);
> else
> return page_to_phys(vmalloc_to_page(addr));
> - } else
> + } else {
> + if ((unsigned long)addr < VMALLOC_START ||
> + (unsigned long)addr >= VMALLOC_END) {
> + static bool first = true;
> + if (first) {
> + WARN_ON(1);
> + printk("XXX addr=%p out of vmalloc area and not in first
> chunk\n", addr);
> + pcpu_dump_chunk_slots();
> + first = false;
> + }
> + return __pa(addr);
> + }
> return page_to_phys(pcpu_addr_to_page(addr));
> + }
> }
>
> /**
> @@ -1283,6 +1332,11 @@ int __init pcpu_setup_first_chunk(const struct
> pcpu_alloc_info *ai,
> pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
> BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
>
> + printk("XXX CPU->UNIT M/O");
> + for_each_possible_cpu(cpu)
> + printk(" %d:%lx", unit_map[cpu], unit_off[cpu]);
> + printk("\n");
> +
> /*
> * Allocate chunk slots. The additional last slot is for
> * empty chunks.
> @@ -1292,6 +1346,10 @@ int __init pcpu_setup_first_chunk(const struct
> pcpu_alloc_info *ai,
> for (i = 0; i < pcpu_nr_slots; i++)
> INIT_LIST_HEAD(&pcpu_slot[i]);
>
> + printk("XXX ss=%zu up=%d us=%d ns=%d rs=%zd ds=%zd\n",
> + ai->static_size, pcpu_unit_pages, pcpu_unit_size,
> + pcpu_nr_slots, ai->reserved_size, dyn_size);
> +
> /*
> * Initialize static chunk. If reserved_size is zero, the
> * static chunk covers static area + dynamic allocation area
> @@ -1311,6 +1369,7 @@ int __init pcpu_setup_first_chunk(const struct
> pcpu_alloc_info *ai,
> schunk->free_size = ai->reserved_size;
> pcpu_reserved_chunk = schunk;
> pcpu_reserved_chunk_limit = ai->static_size + ai->reserved_size;
> + schunk->chunkno = -1;
> } else {
> schunk->free_size = dyn_size;
> dyn_size = 0; /* dynamic area covered */
> @@ -1340,6 +1399,12 @@ int __init pcpu_setup_first_chunk(const struct
> pcpu_alloc_info *ai,
> pcpu_first_chunk = dchunk ?: schunk;
> pcpu_chunk_relocate(pcpu_first_chunk, -1);
>
> + if (pcpu_reserved_chunk) {
> + printk("XXX reserved chunk\n");
> + pcpu_dump_chunk(pcpu_reserved_chunk);
> + }
> + pcpu_dump_chunk_slots();
> +
> /* we're done */
> pcpu_base_addr = base_addr;
> return 0;
> @@ -1623,6 +1688,7 @@ int __init pcpu_embed_first_chunk(size_t
> reserved_size, size_t dyn_size,
> goto out_free_areas;
> }
> areas[group] = ptr;
> + printk("XXX areas[%d]=%p\n", group, areas[group]);
>
> base = min(ptr, base);
>
> @@ -1639,12 +1705,15 @@ int __init pcpu_embed_first_chunk(size_t
> reserved_size, size_t dyn_size,
> }
>
> /* base address is now known, determine group base offsets */
> + printk("XXX base_addr=%p", base);
> max_distance = 0;
> for (group = 0; group < ai->nr_groups; group++) {
> ai->groups[group].base_offset = areas[group] - base;
> max_distance = max_t(size_t, max_distance,
> ai->groups[group].base_offset);
> + printk(" %lx", ai->groups[group].base_offset);
> }
> + printk("\n");
> max_distance += ai->unit_size;
>
> /* warn if maximum distance is further than 75% of vmalloc space */
>
> _______________________________________________
> kexec mailing list
> kexec at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
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