020ec6537aa65c18e9084c568d7b94727f2026fd introduced a regression that an empty vmcore was generated during kdump on a kvm guest.
ioremap: invalid physical address db74000000000000
------------[ cut here ]------------
WARNING: at arch/x86/mm/ioremap.c:83 __ioremap_caller+0x307/0x380()
Hardware name: KVM
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.36-rc2-mm1+ #2
Call Trace:
[<ffffffff8105f48f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff8103052e>] ? copy_oldmem_page+0x4e/0xc0
[<ffffffff8105f4ea>] warn_slowpath_null+0x1a/0x20
[<ffffffff8103f0a7>] __ioremap_caller+0x307/0x380
[<ffffffff8103f1f7>] ioremap_nocache+0x17/0x20
[<ffffffff8103052e>] copy_oldmem_page+0x4e/0xc0
[<ffffffff811af4ca>] read_from_oldmem+0x7a/0xb0
[<ffffffff81c4f70b>] merge_note_headers_elf64.clone.1+0x6c/0x21f
[<ffffffff8103056e>] ? copy_oldmem_page+0x8e/0xc0
[<ffffffff811af4ca>] ? read_from_oldmem+0x7a/0xb0
[<ffffffff81c4fa5b>] vmcore_init+0x19d/0x396
[<ffffffff81c4f8be>] ? vmcore_init+0x0/0x396
[<ffffffff81002053>] do_one_initcall+0x43/0x190
[<ffffffff81c278ab>] kernel_init+0x2a0/0x330
[<ffffffff8100be84>] kernel_thread_helper+0x4/0x10
[<ffffffff81c2760b>] ? kernel_init+0x0/0x330
[<ffffffff8100be80>] ? kernel_thread_helper+0x0/0x10
---[ end trace 93d72a36b9146f22 ]---
Kdump: vmcore not initialized
This patch fixed it by reverting a chunk of the above commit and 9983b6f0cf8263e51bcf4c8a9dc0c1ef175b3c60 which is based on it.
Signed-off-by: CAI Qian <caiqian at redhat.com>
diff --git a/mm/percpu.c b/mm/percpu.c
index 77e3f5a..0dbb12a 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -986,38 +986,10 @@ bool is_kernel_percpu_address(unsigned long addr)
*/
phys_addr_t per_cpu_ptr_to_phys(void *addr)
{
- void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
- bool in_first_chunk = false;
- unsigned long first_start, first_end;
- unsigned int cpu;
-
- /*
- * The following test on first_start/end isn't strictly
- * necessary but will speed up lookups of addresses which
- * aren't in the first chunk.
- */
- first_start = pcpu_chunk_addr(pcpu_first_chunk, pcpu_first_unit_cpu, 0);
- first_end = pcpu_chunk_addr(pcpu_first_chunk, pcpu_last_unit_cpu,
- pcpu_unit_pages);
- if ((unsigned long)addr >= first_start &&
- (unsigned long)addr < first_end) {
- for_each_possible_cpu(cpu) {
- void *start = per_cpu_ptr(base, cpu);
-
- if (addr >= start && addr < start + pcpu_unit_size) {
- in_first_chunk = true;
- break;
- }
- }
- }
-
- if (in_first_chunk) {
- if ((unsigned long)addr < VMALLOC_START ||
- (unsigned long)addr >= VMALLOC_END)
- return __pa(addr);
- else
- return page_to_phys(vmalloc_to_page(addr));
- } else
+ if ((unsigned long)addr < VMALLOC_START ||
+ (unsigned long)addr >= VMALLOC_END)
+ return __pa(addr);
+ else
return page_to_phys(pcpu_addr_to_page(addr));
}
