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Mon, 15 May 2023 05:54:27 GMT Received: from smtpav03.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 70D8B58056; Mon, 15 May 2023 05:54:27 +0000 (GMT) Received: from smtpav03.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BC86358060; Mon, 15 May 2023 05:54:25 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.109.204.255]) by smtpav03.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 15 May 2023 05:54:25 +0000 (GMT) X-Mailer: emacs 29.0.60 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Michael Ellerman , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] powerpc/64s/radix: Fix soft dirty tracking In-Reply-To: <20230511114224.977423-1-mpe@ellerman.id.au> References: <20230511114224.977423-1-mpe@ellerman.id.au> Date: Mon, 15 May 2023 11:24:23 +0530 Message-ID: <87zg66dtrk.fsf@linux.ibm.com> Content-Type: text/plain; charset=utf-8 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: rzX33nCbNPFeOMwYPUVMwjNHWUgbZUg0 X-Proofpoint-ORIG-GUID: CllUFLHZaHPe65veMAx-xyXK3X9vdk0C Content-Transfer-Encoding: quoted-printable X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-05-15_02,2023-05-05_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 spamscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 adultscore=0 phishscore=0 mlxlogscore=960 impostorscore=0 mlxscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000 definitions=main-2305150048 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dan@danny.cz, npiggin@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Michael Ellerman 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 =3D 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 > Fixes: b0b5e9b13047 ("powerpc/mm/radix: Add radix pte #defines") > Cc: stable@vger.kernel.org # v4.7+ > Reported-by: Dan Hor=C3=A1k > Link: https://lore.kernel.org/r/20230511095558.56663a50f86bdc4cd97700b7@d= anny.cz > Signed-off-by: Michael Ellerman > --- > 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/b= ook3s64/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_st= ruct *vma, pte_t *ptep, > pte_t entry, unsigned long address, int psize) > { > struct mm_struct *mm =3D vma->vm_mm; > - unsigned long set =3D pte_val(entry) & (_PAGE_DIRTY | _PAGE_ACCESSED | > - _PAGE_RW | _PAGE_EXEC); > + unsigned long set =3D pte_val(entry) & (_PAGE_DIRTY | _PAGE_SOFT_DIRTY | > + _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC); >=20=20 > unsigned long change =3D pte_val(entry) ^ pte_val(*ptep); > /* > --=20 > 2.40.1