This is a note to let you know that I've just added the patch titled
mm/debug_vm_pgtable: fix BUG_ON with pud advanced test
to the 6.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-debug_vm_pgtable-fix-bug_on-with-pud-advanced-test.patch
and it can be found in the queue-6.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 720da1e593b85a550593b415bf1d79a053133451 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@xxxxxxxxxx>
Date: Mon, 29 Jan 2024 11:30:22 +0530
Subject: mm/debug_vm_pgtable: fix BUG_ON with pud advanced test
From: Aneesh Kumar K.V (IBM) <aneesh.kumar@xxxxxxxxxx>
commit 720da1e593b85a550593b415bf1d79a053133451 upstream.
Architectures like powerpc add debug checks to ensure we find only devmap
PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM.
This patch marks the ptes used for PUD advanced test devmap pte entries so
that we don't hit on debug checks on architecture like ppc64 as below.
WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 radix__pud_hugepage_update+0x38/0x138
...
NIP [c0000000000a7004] radix__pud_hugepage_update+0x38/0x138
LR [c0000000000a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
Call Trace:
[c000000004a2f950] [c000000004a2f9a0] 0xc000000004a2f9a0 (unreliable)
[c000000004a2f980] [000d34c100000000] 0xd34c100000000
[c000000004a2f9a0] [c00000000206ba98] pud_advanced_tests+0x118/0x334
[c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48
[c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388
Also
kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
....
NIP [c000000000096510] pudp_huge_get_and_clear_full+0x98/0x174
LR [c00000000206bb34] pud_advanced_tests+0x1b4/0x334
Call Trace:
[c000000004a2f950] [000d34c100000000] 0xd34c100000000 (unreliable)
[c000000004a2f9a0] [c00000000206bb34] pud_advanced_tests+0x1b4/0x334
[c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48
[c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388
Link: https://lkml.kernel.org/r/20240129060022.68044-1-aneesh.kumar@xxxxxxxxxx
Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
Signed-off-by: Aneesh Kumar K.V (IBM) <aneesh.kumar@xxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -362,6 +362,12 @@ static void __init pud_advanced_tests(st
vaddr &= HPAGE_PUD_MASK;
pud = pfn_pud(args->pud_pfn, args->page_prot);
+ /*
+ * Some architectures have debug checks to make sure
+ * huge pud mapping are only found with devmap entries
+ * For now test with only devmap entries.
+ */
+ pud = pud_mkdevmap(pud);
set_pud_at(args->mm, vaddr, args->pudp, pud);
flush_dcache_page(page);
pudp_set_wrprotect(args->mm, vaddr, args->pudp);
@@ -374,6 +380,7 @@ static void __init pud_advanced_tests(st
WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */
pud = pfn_pud(args->pud_pfn, args->page_prot);
+ pud = pud_mkdevmap(pud);
pud = pud_wrprotect(pud);
pud = pud_mkclean(pud);
set_pud_at(args->mm, vaddr, args->pudp, pud);
@@ -391,6 +398,7 @@ static void __init pud_advanced_tests(st
#endif /* __PAGETABLE_PMD_FOLDED */
pud = pfn_pud(args->pud_pfn, args->page_prot);
+ pud = pud_mkdevmap(pud);
pud = pud_mkyoung(pud);
set_pud_at(args->mm, vaddr, args->pudp, pud);
flush_dcache_page(page);
Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxx are
queue-6.7/mm-debug_vm_pgtable-fix-bug_on-with-pud-advanced-test.patch
