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bh=jOumTyFzmApDLmcuzvAmkjZjCGRjQy7iz9BhGJngPAs=; b=SBLm0sJsVFj/JeXuIzZXUJkIvNGaz/h/lJUBUSKzKld+agFD4cpLGwMbBwoBVX9Keu nf2p5/D8KWHy2B++p99uy2hR6mjL2l8V+t9c4cpNNEPhLbiUT2cZijiuXldXA5HodX/H Ylmi72eWZbkMaNUChltD0l/d6/6fecowhWVjwQOADC1NrgKYQHavBOvdgdCHpZlSFs6P yHFFwTlD8DpdsR4Avi+6Rl/Wth8204/eWwyATm06fImIpIXUpG/BKOdELcR0tAX0KEM1 kfNm58UnjZvq0MNJ1ea+GUu3L/8S6K0nu3AAqC+c7JoMw/3Y9aAuUwlGHOT2lFR7SovA VeRA== X-Forwarded-Encrypted: i=1; AJvYcCU707jUfFLniEcoXxqJfWOOxsQ59Bt8e3J9yNIR9kWJA0RGwI90iiBBWo+bjfOUme0hPbdaBK+UOA==@kvack.org X-Gm-Message-State: AOJu0YzTz7j1TExSaFneQvQujjls/4eZDK83oYYye7lSKc+Qivi9gi+5 Dy3SJ+6bnVhAqGIjH/cZzL6QNZ91UIXPtaRnBAi/LkuEQbzPJx78qZp7P360GCDvalKxS/bVjkK iMgLgLN/OVGUjs2Yc4sKkONC49DQ= X-Google-Smtp-Source: AGHT+IGeaI3XwXhVCcs8TxI+CxKj5y2PoN9gQ5vAHJWzKcaD+balY7FmQ98EIi8Y2Bt/iggITxsbQ88QZD7qSpDURVk= X-Received: by 2002:a05:6102:510b:b0:49b:fe6b:493e with SMTP id ada2fe7eead31-49d4f6ee970mr12877891137.24.1726709891536; Wed, 18 Sep 2024 18:38:11 -0700 (PDT) MIME-Version: 1.0 References: <20240916110754.1236200-1-dev.jain@arm.com> <20240916110754.1236200-2-dev.jain@arm.com> In-Reply-To: <20240916110754.1236200-2-dev.jain@arm.com> From: Barry Song Date: Thu, 19 Sep 2024 13:38:00 +1200 Message-ID: Subject: Re: [PATCH v2 1/2] mm: Make pte_range_none() return number of empty PTEs To: Dev Jain Cc: akpm@linux-foundation.org, david@redhat.com, willy@infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, hughd@google.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, baolin.wang@linux.alibaba.com, gshan@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7B79140012 X-Stat-Signature: oyyqamex7e5ma5i9zg1f6datfh3pctnc X-Rspam-User: X-Rspamd-Pre-Result: action=add header; module=dmarc; Action set by DMARC X-Rspam: Yes X-HE-Tag: 1726709892-663848 X-HE-Meta: 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 KYSmlCde HIhEKdbSWIGjO5iUUuK7hanpVeqruaH/tg4kuGvJMhNRsvfbYTdoFagRvfDu62AOerdP8RrlQGFPaXd29I93TP7fKi9IwMjkuvVRTjII+AZzOHbT6ifhMc3Y/T+wV4dt/wAvp4GDH9LZYPIcWvW80WyOI1v4FNa62WwYFypVyaTk4L9VBqHu8oFgUnCeI7FJP9qKVDm+cJIIMEsU1HKeZ+zmtEf+l9R4BDlkI8ga4+GAJg3ZpsIqf1sb58YFhRXH70VmEbf9N6nsM2hcLdI/ConSE9+P6gnnzeB7brqFOUbaL/xp84kBDDI1mafRS+TNT17OVd93XFyTcshOibHl2ALMdEIrzLqwIGneiBxg8tIIgmwxw9R5CsuK6mfbHdDpzzOMKj+4wms32vDSwi89tf2fKmKle8qs8eD3a X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, 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 Mon, Sep 16, 2024 at 11:08=E2=80=AFPM Dev Jain wrote: > > In preparation for the second patch, make pte_range_none() return > the number of contiguous empty PTEs. > > Signed-off-by: Dev Jain > --- > mm/memory.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 6469ac99f2f7..8bb1236de93c 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4617,16 +4617,16 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > return ret; > } > > -static bool pte_range_none(pte_t *pte, int nr_pages) > +static int pte_range_none(pte_t *pte, int nr_pages) > { > int i; > > for (i =3D 0; i < nr_pages; i++) { > if (!pte_none(ptep_get_lockless(pte + i))) > - return false; > + return i; > } > > - return true; > + return nr_pages; > } > > static struct folio *alloc_anon_folio(struct vm_fault *vmf) > @@ -4671,7 +4671,7 @@ static struct folio *alloc_anon_folio(struct vm_fau= lt *vmf) > order =3D highest_order(orders); > while (orders) { > addr =3D ALIGN_DOWN(vmf->address, PAGE_SIZE << order); > - if (pte_range_none(pte + pte_index(addr), 1 << order)) > + if (pte_range_none(pte + pte_index(addr), 1 << order) =3D= =3D 1 << order) Minor suggestion: it's a bit odd that we're doing 1 << order twice. Perhaps consider introducing a local variable, nr_pages, for clarity. Otherwise, Reviewed-by: Barry Song > break; > order =3D next_order(&orders, order); > } > @@ -4787,7 +4787,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault= *vmf) > if (nr_pages =3D=3D 1 && vmf_pte_changed(vmf)) { > update_mmu_tlb(vma, addr, vmf->pte); > goto release; > - } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { > + } else if (nr_pages > 1 && pte_range_none(vmf->pte, nr_pages) != =3D nr_pages) { > update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); > goto release; > } > @@ -5121,7 +5121,7 @@ vm_fault_t finish_fault(struct vm_fault *vmf) > update_mmu_tlb(vma, addr, vmf->pte); > ret =3D VM_FAULT_NOPAGE; > goto unlock; > - } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { > + } else if (nr_pages > 1 && pte_range_none(vmf->pte, nr_pages) != =3D nr_pages) { > update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); > ret =3D VM_FAULT_NOPAGE; > goto unlock; > -- > 2.30.2 > Thanks Barry