From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leonardo Bras Subject: [PATCH v4 03/11] mm/gup: Applies counting method to monitor gup_pgd_range Date: Fri, 27 Sep 2019 20:40:00 -0300 Message-ID: <20190927234008.11513-4-leonardo@linux.ibm.com> References: <20190927234008.11513-1-leonardo@linux.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190927234008.11513-1-leonardo@linux.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Cc: Leonardo Bras , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Arnd Bergmann , "Aneesh Kumar K.V" , Christophe Leroy , Andrew Morton , Dan Williams , Nicholas Piggin , Mahesh Salgaonkar , Allison Randal , Thomas Gleixner , Ganesh Goudar , Mike Rapoport , YueHaibing , Greg Kroah-Hartman , Ira Weiny , Jason Gunthorpe List-Id: linux-arch.vger.kernel.org As decribed, gup_pgd_range is a lockless pagetable walk. So, in order to monitor against THP split/collapse with the couting method, it's necessary to bound it with {start,end}_lockless_pgtbl_walk. There are dummy functions, so it is not going to add any overhead on archs that don't use this method. Signed-off-by: Leonardo Bras --- mm/gup.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index 98f13ab37bac..7105c829cf44 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2325,6 +2325,7 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end) int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { + struct mm_struct *mm; unsigned long len, end; unsigned long flags; int nr = 0; @@ -2352,9 +2353,12 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { + mm = current->mm; + start_lockless_pgtbl_walk(mm); local_irq_save(flags); gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr); local_irq_restore(flags); + end_lockless_pgtbl_walk(mm); } return nr; @@ -2404,6 +2408,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, unsigned int gup_flags, struct page **pages) { unsigned long addr, len, end; + struct mm_struct *mm; int nr = 0, ret = 0; if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM))) @@ -2421,9 +2426,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages, if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { + mm = current->mm; + start_lockless_pgtbl_walk(mm); local_irq_disable(); gup_pgd_range(addr, end, gup_flags, pages, &nr); local_irq_enable(); + end_lockless_pgtbl_walk(mm); ret = nr; } -- 2.20.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:12834 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728487AbfI0XlQ (ORCPT ); Fri, 27 Sep 2019 19:41:16 -0400 From: Leonardo Bras Subject: [PATCH v4 03/11] mm/gup: Applies counting method to monitor gup_pgd_range Date: Fri, 27 Sep 2019 20:40:00 -0300 Message-ID: <20190927234008.11513-4-leonardo@linux.ibm.com> In-Reply-To: <20190927234008.11513-1-leonardo@linux.ibm.com> References: <20190927234008.11513-1-leonardo@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Cc: Leonardo Bras , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Arnd Bergmann , "Aneesh Kumar K.V" , Christophe Leroy , Andrew Morton , Dan Williams , Nicholas Piggin , Mahesh Salgaonkar , Allison Randal , Thomas Gleixner , Ganesh Goudar , Mike Rapoport , YueHaibing , Greg Kroah-Hartman , Ira Weiny , Jason Gunthorpe , John Hubbard , Keith Busch Message-ID: <20190927234000.zI9c-XJq5RCpjrrt9ualnFjXS-hx0bLqtynz_NGgrHQ@z> As decribed, gup_pgd_range is a lockless pagetable walk. So, in order to monitor against THP split/collapse with the couting method, it's necessary to bound it with {start,end}_lockless_pgtbl_walk. There are dummy functions, so it is not going to add any overhead on archs that don't use this method. Signed-off-by: Leonardo Bras --- mm/gup.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index 98f13ab37bac..7105c829cf44 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2325,6 +2325,7 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end) int __get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { + struct mm_struct *mm; unsigned long len, end; unsigned long flags; int nr = 0; @@ -2352,9 +2353,12 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { + mm = current->mm; + start_lockless_pgtbl_walk(mm); local_irq_save(flags); gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr); local_irq_restore(flags); + end_lockless_pgtbl_walk(mm); } return nr; @@ -2404,6 +2408,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, unsigned int gup_flags, struct page **pages) { unsigned long addr, len, end; + struct mm_struct *mm; int nr = 0, ret = 0; if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM))) @@ -2421,9 +2426,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages, if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { + mm = current->mm; + start_lockless_pgtbl_walk(mm); local_irq_disable(); gup_pgd_range(addr, end, gup_flags, pages, &nr); local_irq_enable(); + end_lockless_pgtbl_walk(mm); ret = nr; } -- 2.20.1