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AJvYcCXia/S3tOdDtrlAwYgzHMeT1UZjsouBhNs6QJq3qDNtFWB+KpvPXy6tUDXlsm6cjsdI6EdbeJirz92KQBzbh3f4jAg= X-Gm-Message-State: AOJu0YyeEr/tjdLsanaRwed4BXWG4E32HLKbXUDX8KR/J+0FQIz8SQLS vtxFT0JRWW+cqqe88gMCahqvi99MdOyLvKyVmEh1OFdURTX3unBM1IzhudLZGFd8fiEMPJ2GHb5 0lsvoCx3hSxkkhbYn5YZsUsB8Rn0= X-Google-Smtp-Source: AGHT+IGb0voqCV585bpnH/J5W+v/xJ2//oAE1LH+cwuaGoFXpWugv68iXzM/VTm06QxP12zL7+mFnbOKAwiQZOkBNuo= X-Received: by 2002:a50:cd0b:0:b0:56e:3f0:a163 with SMTP id z11-20020a50cd0b000000b0056e03f0a163mr13529487edi.14.1713327429158; Tue, 16 Apr 2024 21:17:09 -0700 (PDT) MIME-Version: 1.0 References: <20240416033457.32154-1-ioworker0@gmail.com> <20240416033457.32154-3-ioworker0@gmail.com> <456de31b-221f-4aeb-a2d3-9bb318526417@arm.com> In-Reply-To: <456de31b-221f-4aeb-a2d3-9bb318526417@arm.com> From: Lance Yang Date: Wed, 17 Apr 2024 12:16:58 +0800 Message-ID: Subject: Re: [PATCH v7 2/3] mm/arm64: override clear_young_dirty_ptes() batch helper To: Ryan Roberts Cc: akpm@linux-foundation.org, david@redhat.com, 21cnbao@gmail.com, mhocko@suse.com, fengwei.yin@intel.com, zokeefe@google.com, shy828301@gmail.com, xiehuan09@gmail.com, wangkefeng.wang@huawei.com, songmuchun@bytedance.com, peterx@redhat.com, minchan@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: F021440006 X-Rspam-User: X-Stat-Signature: i5hoemnaf4wqd1cuqdu56ehp7ewge48h X-HE-Tag: 1713327430-468701 X-HE-Meta: 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 AT352/uv 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 17, 2024 at 12:29=E2=80=AFAM Ryan Roberts wrote: > > On 16/04/2024 04:34, Lance Yang wrote: > > The per-pte get_and_clear/modify/set approach would result in > > unfolding/refolding for contpte mappings on arm64. So we need > > to override clear_young_dirty_ptes() for arm64 to avoid it. > > > > Suggested-by: David Hildenbrand > > Suggested-by: Barry Song <21cnbao@gmail.com> > > Suggested-by: Ryan Roberts > > Signed-off-by: Lance Yang > > Reviewed-by: Ryan Roberts Hey Ryan, Thanks for taking time to review! Best, Lance > > > --- > > arch/arm64/include/asm/pgtable.h | 55 ++++++++++++++++++++++++++++++++ > > arch/arm64/mm/contpte.c | 29 +++++++++++++++++ > > 2 files changed, 84 insertions(+) > > > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/= pgtable.h > > index 9fd8613b2db2..1303d30287dc 100644 > > --- a/arch/arm64/include/asm/pgtable.h > > +++ b/arch/arm64/include/asm/pgtable.h > > @@ -1223,6 +1223,46 @@ static inline void __wrprotect_ptes(struct mm_st= ruct *mm, unsigned long address, > > __ptep_set_wrprotect(mm, address, ptep); > > } > > > > +static inline void __clear_young_dirty_pte(struct vm_area_struct *vma, > > + unsigned long addr, pte_t *pte= p, > > + pte_t pte, cydp_t flags) > > +{ > > + pte_t old_pte; > > + > > + do { > > + old_pte =3D pte; > > + > > + if (flags & CYDP_CLEAR_YOUNG) > > + pte =3D pte_mkold(pte); > > + if (flags & CYDP_CLEAR_DIRTY) > > + pte =3D pte_mkclean(pte); > > + > > + pte_val(pte) =3D cmpxchg_relaxed(&pte_val(*ptep), > > + pte_val(old_pte), pte_val(= pte)); > > + } while (pte_val(pte) !=3D pte_val(old_pte)); > > +} > > + > > +static inline void __clear_young_dirty_ptes(struct vm_area_struct *vma= , > > + unsigned long addr, pte_t *pt= ep, > > + unsigned int nr, cydp_t flags= ) > > +{ > > + pte_t pte; > > + > > + for (;;) { > > + pte =3D __ptep_get(ptep); > > + > > + if (flags =3D=3D (CYDP_CLEAR_YOUNG | CYDP_CLEAR_DIRTY)) > > + __set_pte(ptep, pte_mkclean(pte_mkold(pte))); > > + else > > + __clear_young_dirty_pte(vma, addr, ptep, pte, fla= gs); > > + > > + if (--nr =3D=3D 0) > > + break; > > + ptep++; > > + addr +=3D PAGE_SIZE; > > + } > > +} > > + > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > > #define __HAVE_ARCH_PMDP_SET_WRPROTECT > > static inline void pmdp_set_wrprotect(struct mm_struct *mm, > > @@ -1379,6 +1419,9 @@ extern void contpte_wrprotect_ptes(struct mm_stru= ct *mm, unsigned long addr, > > extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma, > > unsigned long addr, pte_t *ptep, > > pte_t entry, int dirty); > > +extern void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma, > > + unsigned long addr, pte_t *ptep, > > + unsigned int nr, cydp_t flags); > > > > static __always_inline void contpte_try_fold(struct mm_struct *mm, > > unsigned long addr, pte_t *ptep, pte_t pt= e) > > @@ -1603,6 +1646,17 @@ static inline int ptep_set_access_flags(struct v= m_area_struct *vma, > > return contpte_ptep_set_access_flags(vma, addr, ptep, entry, dirt= y); > > } > > > > +#define clear_young_dirty_ptes clear_young_dirty_ptes > > +static inline void clear_young_dirty_ptes(struct vm_area_struct *vma, > > + unsigned long addr, pte_t *ptep= , > > + unsigned int nr, cydp_t flags) > > +{ > > + if (likely(nr =3D=3D 1 && !pte_cont(__ptep_get(ptep)))) > > + __clear_young_dirty_ptes(vma, addr, ptep, nr, flags); > > + else > > + contpte_clear_young_dirty_ptes(vma, addr, ptep, nr, flags= ); > > +} > > + > > #else /* CONFIG_ARM64_CONTPTE */ > > > > #define ptep_get __ptep_get > > @@ -1622,6 +1676,7 @@ static inline int ptep_set_access_flags(struct vm= _area_struct *vma, > > #define wrprotect_ptes __wrprotect_ptes > > #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS > > #define ptep_set_access_flags __ptep_set_access= _flags > > +#define clear_young_dirty_ptes __clear_young_dir= ty_ptes > > > > #endif /* CONFIG_ARM64_CONTPTE */ > > > > diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c > > index 1b64b4c3f8bf..9f9486de0004 100644 > > --- a/arch/arm64/mm/contpte.c > > +++ b/arch/arm64/mm/contpte.c > > @@ -361,6 +361,35 @@ void contpte_wrprotect_ptes(struct mm_struct *mm, = unsigned long addr, > > } > > EXPORT_SYMBOL_GPL(contpte_wrprotect_ptes); > > > > +void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma, > > + unsigned long addr, pte_t *ptep, > > + unsigned int nr, cydp_t flags) > > +{ > > + /* > > + * We can safely clear access/dirty without needing to unfold fro= m > > + * the architectures perspective, even when contpte is set. If th= e > > + * range starts or ends midway through a contpte block, we can ju= st > > + * expand to include the full contpte block. While this is not > > + * exactly what the core-mm asked for, it tracks access/dirty per > > + * folio, not per page. And since we only create a contpte block > > + * when it is covered by a single folio, we can get away with > > + * clearing access/dirty for the whole block. > > + */ > > + unsigned long start =3D addr; > > + unsigned long end =3D start + nr; > > + > > + if (pte_cont(__ptep_get(ptep + nr - 1))) > > + end =3D ALIGN(end, CONT_PTE_SIZE); > > + > > + if (pte_cont(__ptep_get(ptep))) { > > + start =3D ALIGN_DOWN(start, CONT_PTE_SIZE); > > + ptep =3D contpte_align_down(ptep); > > + } > > + > > + __clear_young_dirty_ptes(vma, start, ptep, end - start, flags); > > +} > > +EXPORT_SYMBOL_GPL(contpte_clear_young_dirty_ptes); > > + > > int contpte_ptep_set_access_flags(struct vm_area_struct *vma, > > unsigned long addr, pte_t *ptep, > > pte_t entry, int dirty) >