On Tue, Dec 01 2020 at 15:45, Corentin Labbe wrote:
> On Tue, Dec 01, 2020 at 03:16:36PM +0100, Thomas Gleixner wrote:
> In fact the warn was a bit later so I added:
> preempt_disable();
> idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
> - WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
> + if (WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx)))
> + pr_err("kunmap_local: vaddr %lx\n", (unsigned long) vaddr);
>
> arch_kmap_local_pre_unmap(addr);
> pte_clear(&init_mm, addr, kmap_pte - idx);
>
> and this give kunmap_local: vaddr ffefe000
which looks like a valid one.
Can you apply the patch below and add 'ftrace_dump_on_oops' on the
command line or enable it in /proc/sys/kernel/ftrace_dump_on_oops before
starting the test.
That should spill out the trace after crashing.
Thanks,
tglx
---
diff --git a/mm/highmem.c b/mm/highmem.c
index b49364a306b8..461fe2c26107 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -485,6 +485,7 @@ static inline bool kmap_high_unmap_local(unsigned long vaddr)
{
#ifdef ARCH_NEEDS_KMAP_HIGH_GET
if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
+ trace_printk("kunmap_high: %lx\n", vaddr);
kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
return true;
}
@@ -520,6 +521,7 @@ void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
preempt_disable();
idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+ trace_printk("kmap_local_pfn: %d %lx\n", idx, (unsigned long) vaddr);
BUG_ON(!pte_none(*(kmap_pte - idx)));
pteval = pfn_pte(pfn, prot);
set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval);
@@ -545,8 +547,10 @@ void *__kmap_local_page_prot(struct page *page, pgprot_t prot)
/* Try kmap_high_get() if architecture has it enabled */
kmap = arch_kmap_local_high_get(page);
- if (kmap)
+ if (kmap) {
+ trace_printk("kmap_local_high_get: %lx\n", (unsigned long) kmap);
return kmap;
+ }
return __kmap_local_pfn_prot(page_to_pfn(page), prot);
}
@@ -578,6 +582,7 @@ void kunmap_local_indexed(void *vaddr)
preempt_disable();
idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
+ trace_printk("kunmap_local: %i %lx\n", idx, (unsigned long) vaddr);
WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
arch_kmap_local_pre_unmap(addr);
