From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@lists.ozlabs.org
Cc: dan@danny.cz, npiggin@gmail.com
Subject: Re: [PATCH] powerpc/64s/radix: Fix soft dirty tracking
Date: Mon, 15 May 2023 11:24:23 +0530 [thread overview]
Message-ID: <87zg66dtrk.fsf@linux.ibm.com> (raw)
In-Reply-To: <20230511114224.977423-1-mpe@ellerman.id.au>
Michael Ellerman <mpe@ellerman.id.au> writes:
> It was reported that soft dirty tracking doesn't work when using the
> Radix MMU.
>
> The tracking is supposed to work by clearing the soft dirty bit for a
> mapping and then write protecting the PTE. If/when the page is written
> to, a page fault occurs and the soft dirty bit is added back via
> pte_mkdirty(). For example in wp_page_reuse():
>
> entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
> update_mmu_cache(vma, vmf->address, vmf->pte);
>
> Unfortunately on radix _PAGE_SOFTDIRTY is being dropped by
> radix__ptep_set_access_flags(), called from ptep_set_access_flags(),
> meaning the soft dirty bit is not set even though the page has been
> written to.
>
> Fix it by adding _PAGE_SOFTDIRTY to the set of bits that are able to be
> changed in radix__ptep_set_access_flags().
>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Fixes: b0b5e9b13047 ("powerpc/mm/radix: Add radix pte #defines")
> Cc: stable@vger.kernel.org # v4.7+
> Reported-by: Dan Horák <dan@danny.cz>
> Link: https://lore.kernel.org/r/20230511095558.56663a50f86bdc4cd97700b7@danny.cz
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
> arch/powerpc/mm/book3s64/radix_pgtable.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index 26245aaf12b8..2297aa764ecd 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -1040,8 +1040,8 @@ void radix__ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep,
> pte_t entry, unsigned long address, int psize)
> {
> struct mm_struct *mm = vma->vm_mm;
> - unsigned long set = pte_val(entry) & (_PAGE_DIRTY | _PAGE_ACCESSED |
> - _PAGE_RW | _PAGE_EXEC);
> + unsigned long set = pte_val(entry) & (_PAGE_DIRTY | _PAGE_SOFT_DIRTY |
> + _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
>
> unsigned long change = pte_val(entry) ^ pte_val(*ptep);
> /*
> --
> 2.40.1
next prev parent reply other threads:[~2023-05-15 5:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-11 11:42 [PATCH] powerpc/64s/radix: Fix soft dirty tracking Michael Ellerman
2023-05-15 5:54 ` Aneesh Kumar K.V [this message]
2023-05-15 12:43 ` Dan Horák
2023-07-03 5:21 ` Michael Ellerman
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=87zg66dtrk.fsf@linux.ibm.com \
--to=aneesh.kumar@linux.ibm.com \
--cc=dan@danny.cz \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=npiggin@gmail.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.