From: ira.weiny@intel.com
To: Andrew Morton <akpm@linux-foundation.org>,
John Hubbard <jhubbard@nvidia.com>,
Michal Hocko <mhocko@suse.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
"David S. Miller" <davem@davemloft.net>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Rich Felker <dalias@libc.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Ralf Baechle <ralf@linux-mips.org>,
James Hogan <jhogan@kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, linux-rdma@vger.kernel.org,
netdev@vger.kernel.org
Subject: [PATCH V3 4/7] mm/gup: Add FOLL_LONGTERM capability to GUP fast
Date: Thu, 28 Mar 2019 01:44:19 -0700 [thread overview]
Message-ID: <20190328084422.29911-5-ira.weiny@intel.com> (raw)
In-Reply-To: <20190328084422.29911-1-ira.weiny@intel.com>
From: Ira Weiny <ira.weiny@intel.com>
DAX pages were previously unprotected from longterm pins when users
called get_user_pages_fast().
Use the new FOLL_LONGTERM flag to check for DEVMAP pages and fall
back to regular GUP processing if a DEVMAP page is encountered.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
Changes from V2:
Add comment on special use case of FOLL_LONGTERM
mm/gup.c | 40 ++++++++++++++++++++++++++++++++++++----
1 file changed, 36 insertions(+), 4 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 0fa7244d6f19..567bd1b295f0 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1613,6 +1613,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
goto pte_unmap;
if (pte_devmap(pte)) {
+ if (unlikely(flags & FOLL_LONGTERM))
+ goto pte_unmap;
+
pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, pages);
@@ -1752,8 +1755,11 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
return 0;
- if (pmd_devmap(orig))
+ if (pmd_devmap(orig)) {
+ if (unlikely(flags & FOLL_LONGTERM))
+ return 0;
return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr);
+ }
refs = 0;
page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
@@ -1790,8 +1796,11 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
if (!pud_access_permitted(orig, flags & FOLL_WRITE))
return 0;
- if (pud_devmap(orig))
+ if (pud_devmap(orig)) {
+ if (unlikely(flags & FOLL_LONGTERM))
+ return 0;
return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr);
+ }
refs = 0;
page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
@@ -2034,6 +2043,29 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
return nr;
}
+static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
+ unsigned int gup_flags, struct page **pages)
+{
+ int ret;
+
+ /*
+ * FIXME: FOLL_LONGTERM does not work with
+ * get_user_pages_unlocked() (see comments in that function)
+ */
+ if (gup_flags & FOLL_LONGTERM) {
+ down_read(¤t->mm->mmap_sem);
+ ret = __gup_longterm_locked(current, current->mm,
+ start, nr_pages,
+ pages, NULL, gup_flags);
+ up_read(¤t->mm->mmap_sem);
+ } else {
+ ret = get_user_pages_unlocked(start, nr_pages,
+ pages, gup_flags);
+ }
+
+ return ret;
+}
+
/**
* get_user_pages_fast() - pin user pages in memory
* @start: starting user address
@@ -2079,8 +2111,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
start += nr << PAGE_SHIFT;
pages += nr;
- ret = get_user_pages_unlocked(start, nr_pages - nr, pages,
- gup_flags);
+ ret = __gup_longterm_unlocked(start, nr_pages - nr,
+ gup_flags, pages);
/* Have to be a bit careful with return values */
if (nr > 0) {
--
2.20.1
next prev parent reply other threads:[~2019-03-28 16:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-28 8:44 [PATCH V3 0/7] Add FOLL_LONGTERM to GUP fast and use it ira.weiny
2019-03-28 8:44 ` [PATCH V3 1/7] mm/gup: Replace get_user_pages_longterm() with FOLL_LONGTERM ira.weiny
2019-03-28 8:44 ` [PATCH V3 2/7] mm/gup: Change write parameter to flags in fast walk ira.weiny
2019-03-28 8:44 ` [PATCH V3 3/7] mm/gup: Change GUP fast to use flags rather than a write 'bool' ira.weiny
2019-03-28 8:44 ` ira.weiny [this message]
2019-03-28 8:44 ` [PATCH V3 5/7] IB/hfi1: Use the new FOLL_LONGTERM flag to get_user_pages_fast() ira.weiny
2019-03-28 8:44 ` [PATCH V3 6/7] IB/qib: " ira.weiny
2019-03-28 8:44 ` [PATCH V3 7/7] IB/mthca: " ira.weiny
2019-04-09 0:13 ` [PATCH V3 0/7] Add FOLL_LONGTERM to GUP fast and use it Ira Weiny
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