From: Anshuman Khandual <anshuman.khandual@arm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
linux-mm@kvack.org, akpm@linux-foundation.org
Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org, x86@kernel.org,
linux-arch@vger.kernel.org,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Vineet Gupta <vgupta@synopsys.com>,
Mike Rapoport <rppt@linux.ibm.com>, Qian Cai <cai@lca.pw>
Subject: Re: [PATCH v3 13/13] mm/debug_vm_pgtable: populate a pte entry before fetching it
Date: Tue, 1 Sep 2020 08:55:56 +0530 [thread overview]
Message-ID: <edc68223-7f8a-13df-68eb-9682f585adb8@arm.com> (raw)
In-Reply-To: <20200827080438.315345-14-aneesh.kumar@linux.ibm.com>
On 08/27/2020 01:34 PM, 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@linux.ibm.com>
> ---
> mm/debug_vm_pgtable.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 21329c7d672f..8527ebb75f2c 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -546,7 +546,7 @@ static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
> static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
> unsigned long vaddr)
> {
> - pte_t pte = ptep_get(ptep);
> + pte_t pte = ptep_get_and_clear(mm, vaddr, ptep);
Seems like ptep_get_and_clear() here just clears the entry in preparation
for a following set_pte_at() which otherwise would have been a problem on
ppc64 as you had pointed out earlier i.e set_pte_at() should not update an
existing valid entry. So the commit message here is bit misleading.
>
> pr_debug("Validating PTE clear\n");
> pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
> @@ -944,7 +944,7 @@ static int __init debug_vm_pgtable(void)
> p4d_t *p4dp, *saved_p4dp;
> pud_t *pudp, *saved_pudp;
> pmd_t *pmdp, *saved_pmdp, pmd;
> - pte_t *ptep;
> + pte_t *ptep, pte;
> pgtable_t saved_ptep;
> pgprot_t prot, protnone;
> phys_addr_t paddr;
> @@ -1049,6 +1049,8 @@ static int __init debug_vm_pgtable(void)
> */
>
> ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl);
> + pte = pfn_pte(pte_aligned, prot);
> + set_pte_at(mm, vaddr, ptep, pte);
Not here, creating and populating an entry must be done in respective
test functions itself. Besides, this seems bit redundant as well. The
test pte_clear_tests() with the above change added, already
- Clears the PTEP entry with ptep_get_and_clear()
- Creates and populates the PTEP with set_pte_at()
- Clears with pte_clear()
- Checks for pte_none()
If the objective is to clear the PTEP entry before calling set_pte_at(),
then only the first chunk is required and it should also be merged with
a previous patch.
[PATCH v3 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry
> pte_clear_tests(mm, ptep, vaddr);
> pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
> pte_unmap_unlock(ptep, ptl);
>
There is a checkpatch.pl warning here.
WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#7:
pte_clear_tests operate on an existing pte entry. Make sure that is not a none
total: 0 errors, 1 warnings, 24 lines checked
There is also a build failure on x86 reported from kernel test robot.
next prev parent reply other threads:[~2020-09-01 3:26 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 8:04 [PATCH v3 00/13] mm/debug_vm_pgtable fixes Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 01/13] powerpc/mm: Add DEBUG_VM WARN for pmd_clear Aneesh Kumar K.V
2020-09-01 3:12 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 02/13] powerpc/mm: Move setting pte specific flags to pfn_pte Aneesh Kumar K.V
2020-09-01 3:13 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value Aneesh Kumar K.V
2020-09-01 3:15 ` Anshuman Khandual
2020-09-01 6:21 ` Aneesh Kumar K.V
2020-09-01 7:32 ` Anshuman Khandual
2020-09-01 7:36 ` Aneesh Kumar K.V
2020-09-01 7:46 ` Anshuman Khandual
2020-09-01 7:55 ` Aneesh Kumar K.V
2020-09-02 3:45 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 04/13] mm/debug_vm_pgtables/hugevmap: Use the arch helper to identify huge vmap support Aneesh Kumar K.V
2020-09-01 3:16 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 05/13] mm/debug_vm_pgtable/savedwrite: Enable savedwrite test with CONFIG_NUMA_BALANCING Aneesh Kumar K.V
2020-09-01 3:18 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 06/13] mm/debug_vm_pgtable/THP: Mark the pte entry huge before using set_pmd/pud_at Aneesh Kumar K.V
2020-09-01 3:21 ` Anshuman Khandual
2020-09-01 6:23 ` Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 08/13] mm/debug_vm_pgtable/thp: Use page table depost/withdraw with THP Aneesh Kumar K.V
2020-09-01 3:22 ` Anshuman Khandual
2020-09-01 6:25 ` Aneesh Kumar K.V
2020-09-01 6:50 ` Christophe Leroy
2020-09-01 7:40 ` Aneesh Kumar K.V
2020-09-01 7:51 ` Christophe Leroy
2020-09-02 3:45 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 09/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together Aneesh Kumar K.V
2020-09-01 3:41 ` Anshuman Khandual
2020-09-01 6:38 ` Aneesh Kumar K.V
2020-09-01 9:33 ` Anshuman Khandual
2020-09-01 9:36 ` Aneesh Kumar K.V
2020-09-01 9:58 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 10/13] mm/debug_vm_pgtable/locks: Take correct page table lock Aneesh Kumar K.V
2020-09-01 3:44 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 11/13] mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 12/13] mm/debug_vm_pgtable/hugetlb: Disable hugetlb test on ppc64 Aneesh Kumar K.V
2020-09-01 4:03 ` Anshuman Khandual
2020-09-01 6:30 ` Aneesh Kumar K.V
2020-09-01 7:59 ` Christophe Leroy
2020-09-02 13:05 ` Anshuman Khandual
2020-09-02 13:20 ` Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 13/13] mm/debug_vm_pgtable: populate a pte entry before fetching it Aneesh Kumar K.V
2020-08-27 12:17 ` kernel test robot
2020-09-01 3:25 ` Anshuman Khandual [this message]
2020-09-01 6:37 ` Aneesh Kumar K.V
2020-09-01 7:38 ` Anshuman Khandual
2020-09-01 9:58 ` Aneesh Kumar K.V
2020-09-02 3:49 ` Anshuman Khandual
2020-09-02 3:58 ` Aneesh Kumar K.V
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=edc68223-7f8a-13df-68eb-9682f585adb8@arm.com \
--to=anshuman.khandual@arm.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.ibm.com \
--cc=cai@lca.pw \
--cc=christophe.leroy@c-s.fr \
--cc=gerald.schaefer@de.ibm.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=rppt@linux.ibm.com \
--cc=vgupta@synopsys.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).