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Tue, 30 Jun 2020 13:45:14 -0700 (PDT) Received: from xz-x1.redhat.com ([2607:9880:19c0:32::2]) by smtp.gmail.com with ESMTPSA id p80sm3991738qke.19.2020.06.30.13.45.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2020 13:45:13 -0700 (PDT) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , peterx@redhat.com, John Hubbard , Michael Ellerman , Gerald Schaefer , Andrea Arcangeli , Linus Torvalds , Will Deacon , Russell King , linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 04/26] mm/arm: Use general page fault accounting Date: Tue, 30 Jun 2020 16:45:11 -0400 Message-Id: <20200630204511.38663-1-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 4901C1814B0C9 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 Content-Transfer-Encoding: quoted-printable 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: Use the general page fault accounting by passing regs into handle_mm_faul= t(). It naturally solve the issue of multiple page fault accounting when page = fault retry happened. To do this, we need to pass the pt_regs pointer into __do_page_fault(). Fix PERF_COUNT_SW_PAGE_FAULTS perf event manually for page fault retries,= by moving it before taking mmap_sem. CC: Russell King CC: Will Deacon CC: linux-arm-kernel@lists.infradead.org Signed-off-by: Peter Xu --- arch/arm/mm/fault.c | 25 ++++++------------------- 1 file changed, 6 insertions(+), 19 deletions(-) diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 01a8e0f8fef7..efa402025031 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -202,7 +202,8 @@ static inline bool access_error(unsigned int fsr, str= uct vm_area_struct *vma) =20 static vm_fault_t __kprobes __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int f= sr, - unsigned int flags, struct task_struct *tsk) + unsigned int flags, struct task_struct *tsk, + struct pt_regs *regs) { struct vm_area_struct *vma; vm_fault_t fault; @@ -224,7 +225,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long a= ddr, unsigned int fsr, goto out; } =20 - return handle_mm_fault(vma, addr & PAGE_MASK, flags, NULL); + return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs); =20 check_stack: /* Don't allow expansion below FIRST_USER_ADDRESS */ @@ -266,6 +267,8 @@ do_page_fault(unsigned long addr, unsigned int fsr, s= truct pt_regs *regs) if ((fsr & FSR_WRITE) && !(fsr & FSR_CM)) flags |=3D FAULT_FLAG_WRITE; =20 + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); + /* * As per x86, we may deadlock here. However, since the kernel only * validly references user space from well defined areas of the code, @@ -290,7 +293,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, s= truct pt_regs *regs) #endif } =20 - fault =3D __do_page_fault(mm, addr, fsr, flags, tsk); + fault =3D __do_page_fault(mm, addr, fsr, flags, tsk, regs); =20 /* If we need to retry but a fatal signal is pending, handle the * signal first. We do not need to release the mmap_lock because @@ -302,23 +305,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, = struct pt_regs *regs) return 0; } =20 - /* - * Major/minor page fault accounting is only done on the - * initial attempt. If we go through a retry, it is extremely - * likely that the page will be found in page cache at that point. - */ - - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) { - if (fault & VM_FAULT_MAJOR) { - tsk->maj_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, - regs, addr); - } else { - tsk->min_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, - regs, addr); - } if (fault & VM_FAULT_RETRY) { flags |=3D FAULT_FLAG_TRIED; goto retry; --=20 2.26.2