[PATCH v4 13/13] mm/debug_vm_pgtable: Avoid none pte in pte_clear_test
Nathan Chancellor
natechancellor at gmail.com
Fri Sep 11 12:13:58 AEST 2020
On Wed, Sep 02, 2020 at 05:12:22PM +0530, Aneesh Kumar K.V wrote:
> pte_clear_tests operate on an existing pte entry. Make sure that
> is not a none pte entry.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
> mm/debug_vm_pgtable.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 9afa1354326b..c36530c69e33 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -542,9 +542,10 @@ static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
> #endif /* PAGETABLE_P4D_FOLDED */
>
> static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
> - unsigned long vaddr)
> + unsigned long pfn, unsigned long vaddr,
> + pgprot_t prot)
> {
> - pte_t pte = ptep_get(ptep);
> + pte_t pte = pfn_pte(pfn, prot);
>
> pr_debug("Validating PTE clear\n");
> pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
> @@ -1049,7 +1050,7 @@ static int __init debug_vm_pgtable(void)
>
> ptl = pte_lockptr(mm, pmdp);
> spin_lock(ptl);
> - pte_clear_tests(mm, ptep, vaddr);
> + pte_clear_tests(mm, ptep, pte_aligned, vaddr, prot);
> pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
> pte_unmap_unlock(ptep, ptl);
>
> --
> 2.26.2
>
>
This patch causes a panic at boot for RISC-V defconfig. The rootfs is here if it is needed:
https://github.com/ClangBuiltLinux/boot-utils/blob/3b21a5b71451742866349ba4f18638c5a754e660/images/riscv/rootfs.cpio.zst
$ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux- O=out/riscv distclean defconfig Image
$ qemu-system-riscv64 -bios default -M virt -display none -initrd rootfs.cpio -kernel Image -m 512m -nodefaults -serial mon:stdio
...
OpenSBI v0.6
____ _____ ____ _____
/ __ \ / ____| _ \_ _|
| | | |_ __ ___ _ __ | (___ | |_) || |
| | | | '_ \ / _ \ '_ \ \___ \| _ < | |
| |__| | |_) | __/ | | |____) | |_) || |_
\____/| .__/ \___|_| |_|_____/|____/_____|
| |
|_|
Platform Name : QEMU Virt Machine
Platform HART Features : RV64ACDFIMSU
Platform Max HARTs : 8
Current Hart : 0
Firmware Base : 0x80000000
Firmware Size : 120 KB
Runtime SBI Version : 0.2
MIDELEG : 0x0000000000000222
MEDELEG : 0x000000000000b109
PMP0 : 0x0000000080000000-0x000000008001ffff (A)
PMP1 : 0x0000000000000000-0xffffffffffffffff (A,R,W,X)
[ 0.000000] Linux version 5.9.0-rc4-next-20200910 (nathan at ubuntu-n2-xlarge-x86) (riscv64-linux-gcc (GCC) 10.2.0, GNU ld (GNU Binutils) 2.35) #1 SMP Thu Sep 10 19:10:43 MST 2020
...
[ 0.294593] NET: Registered protocol family 17
[ 0.295781] 9pnet: Installing 9P2000 support
[ 0.296153] Key type dns_resolver registered
[ 0.296694] debug_vm_pgtable: [debug_vm_pgtable ]: Validating architecture page table helpers
[ 0.297635] Unable to handle kernel paging request at virtual address 0a7fffe01dafefc8
[ 0.298029] Oops [#1]
[ 0.298153] Modules linked in:
[ 0.298433] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc4-next-20200910 #1
[ 0.298792] epc: ffffffe000205afc ra : ffffffe0008be0aa sp : ffffffe01ae73d40
[ 0.299078] gp : ffffffe0010b9b48 tp : ffffffe01ae68000 t0 : ffffffe008152000
[ 0.299362] t1 : 0000000000000000 t2 : 0000000000000000 s0 : ffffffe01ae73d60
[ 0.299648] s1 : bffffffffffffffb a0 : 0a7fffe01dafefc8 a1 : bffffffffffffffb
[ 0.299948] a2 : ffffffe0010a2698 a3 : 0000000000000001 a4 : 0000000000000003
[ 0.300231] a5 : 0000000000000800 a6 : fffffffff0000080 a7 : 000000001b642000
[ 0.300521] s2 : ffffffe0081517b8 s3 : ffffffe008150a80 s4 : ffffffe01af30000
[ 0.300806] s5 : ffffffe01f8ca9b8 s6 : ffffffe008150000 s7 : ffffffe0010bb100
[ 0.301161] s8 : ffffffe0010bb108 s9 : 0000000000080202 s10: ffffffe0010bb928
[ 0.301481] s11: 000000002008085b t3 : 0000000000000000 t4 : 0000000000000000
[ 0.301722] t5 : 0000000000000000 t6 : ffffffe008150000
[ 0.301947] status: 0000000000000120 badaddr: 0a7fffe01dafefc8 cause: 000000000000000f
[ 0.302569] ---[ end trace 7ffb153d816164cf ]---
[ 0.302797] note: swapper/0[1] exited with preempt_count 1
[ 0.303101] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[ 0.303614] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---
$ git bisect log
# bad: [7ce53e3a447bced7b85ed181c4d027e93c062e07] Add linux-next specific files for 20200910
# good: [34d4ddd359dbcdf6c5fb3f85a179243d7a1cb7f8] Merge tag 'linux-kselftest-5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
git bisect start '7ce53e3a447bced7b85ed181c4d027e93c062e07' '34d4ddd359dbcdf6c5fb3f85a179243d7a1cb7f8'
# good: [bb1f09d126618aa1ec776d87d7f85136edbed485] Merge remote-tracking branch 'crypto/master' into master
git bisect good bb1f09d126618aa1ec776d87d7f85136edbed485
# good: [1fb7e980a0f9a0aa4c7daba1a7e35d12c97820ea] Merge remote-tracking branch 'audit/next' into master
git bisect good 1fb7e980a0f9a0aa4c7daba1a7e35d12c97820ea
# good: [afdf05baff78a658843c1013855985e7a6871406] Merge remote-tracking branch 'thunderbolt/next' into master
git bisect good afdf05baff78a658843c1013855985e7a6871406
# good: [c5f3c031bd4b8ef5fb6b07352abc284603c3edee] Merge remote-tracking branch 'kselftest/next' into master
git bisect good c5f3c031bd4b8ef5fb6b07352abc284603c3edee
# bad: [671aca25e253f2773850aefb0837a225c691e336] lib: bitmap: delete duplicated words
git bisect bad 671aca25e253f2773850aefb0837a225c691e336
# bad: [e42ac710a849403b7fe582cc555dc3b7bf5b6fa9] tools/testing/selftests/vm/hmm-tests.c: use the new SKIP() macro
git bisect bad e42ac710a849403b7fe582cc555dc3b7bf5b6fa9
# good: [1443e3384317a9dfaf1381e8134a69c1e3fc7130] device-dax: kill dax_kmem_res
git bisect good 1443e3384317a9dfaf1381e8134a69c1e3fc7130
# good: [e2aad6f1d232b457ea6a3194992dd4c0a83534a5] mm/debug_vm_pgtable/locks: take correct page table lock
git bisect good e2aad6f1d232b457ea6a3194992dd4c0a83534a5
# bad: [08075d21b791241ba9f1366f814afa4a77372250] mm: workingset: ignore slab memory size when calculating shadows pressure
git bisect bad 08075d21b791241ba9f1366f814afa4a77372250
# bad: [42e9e63856020953cc3645a2032a70179364a1d8] mm-gup-dont-permit-users-to-call-get_user_pages-with-foll_longterm-fix
git bisect bad 42e9e63856020953cc3645a2032a70179364a1d8
# good: [b77bfa2ce4c2e30c1b1d1b3eb18c5b57397277f9] mm/debug_vm_pgtable/hugetlb: disable hugetlb test on ppc64
git bisect good b77bfa2ce4c2e30c1b1d1b3eb18c5b57397277f9
# bad: [90b612d56df39666f0f6fa6a033b4a7ec2e0a16c] mm/gup_benchmark: use pin_user_pages for FOLL_LONGTERM flag
git bisect bad 90b612d56df39666f0f6fa6a033b4a7ec2e0a16c
# bad: [060e70ecf865e55d82282995b4cb478126a1163c] mm/debug_vm_pgtable: avoid none pte in pte_clear_test
git bisect bad 060e70ecf865e55d82282995b4cb478126a1163c
# first bad commit: [060e70ecf865e55d82282995b4cb478126a1163c] mm/debug_vm_pgtable: avoid none pte in pte_clear_test
Cheers,
Nathan
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