Re: [PATCH 0/5] x86/mm/pat: CPA fixes
Nikunj A Dadhania <[email protected]>
| Newsgroups | dev.linux.lists.iommu,org.kernel.vger.linux-kernel,org.kernel.vger.stable,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
On Fri, Aug 07, 2026 at 04:36:08PM +0100, Lorenzo Stoakes (ARM) wrote:
> +static void poke_vmalloc_pages_safe(struct page **pages, void *addr,
> + bool cross_page_boundary)
> +{
> + guard(mmap_read_lock)(&init_mm);
> + poke_vmalloc_pages(pages, addr, cross_page_boundary);
> +}
Tested just the proposed patch from this email (without the rest of the
CPA fixes series) on the 512-guest concurrent boot harness (details in
[1]) and still see the memcmp BUG, I havent hit the first BUG though:
kernel BUG at arch/x86/kernel/alternative.c:2727!
Oops: invalid opcode: 0000 [#1] SMP NOPTI
CPU: 1 UID: 0 PID: 485 Comm: (udev-worker) Not tainted 7.2.0-rc5-pokesafe+ #42 PREEMPT(full)
RIP: 0010:__text_poke.cold+0xdb/0x2af
The instrumentation captured the following before the memcmp BUG:
SMP alternatives: __text_poke: memcmp failed at addr=ffffffffc06ce1bb len=4
SMP alternatives: __text_poke: expected (src): 2e 2e 31 c0
SMP alternatives: __text_poke: found (dst): f9 b8 9b d3
SMP alternatives: __text_poke: pfn at poke time (vmalloc_to_page): 8ece
SMP alternatives: __text_poke: pfn at readback time (vmalloc_to_page): c6ce
SMP alternatives: __text_poke: page table dump for addr:
PGD 2f042067 P4D 2f043067 PUD 2f045067 PMD c6001a1
pfn acquired at the start of __text_poke() (0x8ece) differs from pfn
at readback time (0xc6ce) in the instrumentaion.
[1] https://lore.kernel.org/all/[email protected]/
Regards,
Nikunj