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From: John Hubbard <jhubbard@nvidia.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Dave Chinner" <david@fromorbit.com>,
	"David Airlie" <airlied@linux.ie>,
	"David S . Miller" <davem@davemloft.net>,
	"Jan Kara" <jack@suse.cz>, "Jason Gunthorpe" <jgg@ziepe.ca>,
	"Jens Axboe" <axboe@kernel.dk>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Michal Hocko" <mhocko@suse.com>,
	"Mike Kravetz" <mike.kravetz@oracle.com>,
	"Paul Mackerras" <paulus@samba.org>,
	"Shuah Khan" <shuah@kernel.org>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	bpf@vger.kernel.org, dri-devel@lists.freedesktop.org,
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	netdev@vger.kernel.org, linux-mm@kvack.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 08/19] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote()
Date: Thu, 31 Oct 2019 16:46:45 -0700	[thread overview]
Message-ID: <7e79d9b5-772e-3628-4a60-65efc2f490c5@nvidia.com> (raw)
In-Reply-To: <20191031233519.GH14771@iweiny-DESK2.sc.intel.com>

On 10/31/19 4:35 PM, Ira Weiny wrote:
> On Wed, Oct 30, 2019 at 03:49:19PM -0700, John Hubbard wrote:
>> Convert process_vm_access to use the new pin_user_pages_remote()
>> call, which sets FOLL_PIN. Setting FOLL_PIN is now required for
>> code that requires tracking of pinned pages.
>>
>> Also, release the pages via put_user_page*().
>>
>> Also, rename "pages" to "pinned_pages", as this makes for
>> easier reading of process_vm_rw_single_vec().
> 
> Ok...  but it made review a bit harder...
> 

Yes, sorry about that. After dealing with "pages means struct page *[]"
for all this time, having an "int pages" just was a step too far for
me here. :)

Thanks for working through it. 


thanks,

John Hubbard
NVIDIA



> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> 


>>
>> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
>> ---
>>  mm/process_vm_access.c | 28 +++++++++++++++-------------
>>  1 file changed, 15 insertions(+), 13 deletions(-)
>>
>> diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
>> index 357aa7bef6c0..fd20ab675b85 100644
>> --- a/mm/process_vm_access.c
>> +++ b/mm/process_vm_access.c
>> @@ -42,12 +42,11 @@ static int process_vm_rw_pages(struct page **pages,
>>  		if (copy > len)
>>  			copy = len;
>>  
>> -		if (vm_write) {
>> +		if (vm_write)
>>  			copied = copy_page_from_iter(page, offset, copy, iter);
>> -			set_page_dirty_lock(page);
>> -		} else {
>> +		else
>>  			copied = copy_page_to_iter(page, offset, copy, iter);
>> -		}
>> +
>>  		len -= copied;
>>  		if (copied < copy && iov_iter_count(iter))
>>  			return -EFAULT;
>> @@ -96,7 +95,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
>>  		flags |= FOLL_WRITE;
>>  
>>  	while (!rc && nr_pages && iov_iter_count(iter)) {
>> -		int pages = min(nr_pages, max_pages_per_loop);
>> +		int pinned_pages = min(nr_pages, max_pages_per_loop);
>>  		int locked = 1;
>>  		size_t bytes;
>>  
>> @@ -106,14 +105,15 @@ static int process_vm_rw_single_vec(unsigned long addr,
>>  		 * current/current->mm
>>  		 */
>>  		down_read(&mm->mmap_sem);
>> -		pages = get_user_pages_remote(task, mm, pa, pages, flags,
>> -					      process_pages, NULL, &locked);
>> +		pinned_pages = pin_user_pages_remote(task, mm, pa, pinned_pages,
>> +						     flags, process_pages,
>> +						     NULL, &locked);
>>  		if (locked)
>>  			up_read(&mm->mmap_sem);
>> -		if (pages <= 0)
>> +		if (pinned_pages <= 0)
>>  			return -EFAULT;
>>  
>> -		bytes = pages * PAGE_SIZE - start_offset;
>> +		bytes = pinned_pages * PAGE_SIZE - start_offset;
>>  		if (bytes > len)
>>  			bytes = len;
>>  
>> @@ -122,10 +122,12 @@ static int process_vm_rw_single_vec(unsigned long addr,
>>  					 vm_write);
>>  		len -= bytes;
>>  		start_offset = 0;
>> -		nr_pages -= pages;
>> -		pa += pages * PAGE_SIZE;
>> -		while (pages)
>> -			put_page(process_pages[--pages]);
>> +		nr_pages -= pinned_pages;
>> +		pa += pinned_pages * PAGE_SIZE;
>> +
>> +		/* If vm_write is set, the pages need to be made dirty: */
>> +		put_user_pages_dirty_lock(process_pages, pinned_pages,
>> +					  vm_write);
>>  	}
>>  
>>  	return rc;
>> -- 
>> 2.23.0
>>

  reply	other threads:[~2019-10-31 23:47 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30 22:49 [PATCH 00/19] mm/gup: track dma-pinned pages: FOLL_PIN, FOLL_LONGTERM John Hubbard
2019-10-30 22:49 ` [PATCH 01/19] mm/gup: pass flags arg to __gup_device_* functions John Hubbard
2019-10-31 18:18   ` Ira Weiny
2019-10-30 22:49 ` [PATCH 02/19] mm/gup: factor out duplicate code from four routines John Hubbard
2019-10-31 18:35   ` Ira Weiny
2019-10-31 18:43     ` John Hubbard
2019-10-31 21:09       ` Ira Weiny
2019-10-31 22:01         ` John Hubbard
2019-10-30 22:49 ` [PATCH 03/19] goldish_pipe: rename local pin_user_pages() routine John Hubbard
2019-10-31 18:36   ` Ira Weiny
2019-10-30 22:49 ` [PATCH 04/19] media/v4l2-core: set pages dirty upon releasing DMA buffers John Hubbard
2019-10-30 22:49 ` [PATCH 05/19] mm/gup: introduce pin_user_pages*() and FOLL_PIN John Hubbard
2019-10-31 23:15   ` Ira Weiny
2019-10-31 23:43     ` John Hubbard
2019-10-30 22:49 ` [PATCH 06/19] goldish_pipe: convert to pin_user_pages() and put_user_page() John Hubbard
2019-10-30 22:49 ` [PATCH 07/19] infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*() John Hubbard
2019-10-31 23:25   ` Ira Weiny
2019-10-31 23:49     ` John Hubbard
2019-10-30 22:49 ` [PATCH 08/19] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() John Hubbard
2019-10-31 23:35   ` Ira Weiny
2019-10-31 23:46     ` John Hubbard [this message]
2019-10-30 22:49 ` [PATCH 09/19] drm/via: set FOLL_PIN via pin_user_pages_fast() John Hubbard
2019-10-31 23:36   ` Ira Weiny
2019-11-04 18:10     ` Daniel Vetter
2019-11-04 19:20       ` John Hubbard
2019-11-05  9:49         ` Daniel Vetter
2019-11-05 18:16           ` John Hubbard
2019-10-30 22:49 ` [PATCH 10/19] fs/io_uring: set FOLL_PIN via pin_user_pages() John Hubbard
2019-10-31 23:37   ` Ira Weiny
2019-11-01 14:49   ` Jens Axboe
2019-10-30 22:49 ` [PATCH 11/19] net/xdp: " John Hubbard
2019-10-31 23:37   ` Ira Weiny
2019-11-02 11:01   ` Björn Töpel
2019-10-30 22:49 ` [PATCH 12/19] mm/gup: track FOLL_PIN pages John Hubbard
2019-10-30 22:49 ` [PATCH 13/19] media/v4l2-core: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion John Hubbard
2019-10-31 23:38   ` Ira Weiny
2019-10-30 22:49 ` [PATCH 14/19] vfio, mm: " John Hubbard
2019-10-30 23:05   ` John Hubbard
2019-10-30 22:49 ` [PATCH 15/19] powerpc: book3s64: convert to pin_longterm_pages() and put_user_page() John Hubbard
2019-10-30 22:49 ` [PATCH 16/19] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2019-10-30 22:49 ` [PATCH 17/19] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
2019-10-30 22:49 ` [PATCH 18/19] mm/gup: remove support for gup(FOLL_LONGTERM) John Hubbard
2019-10-30 22:49 ` [PATCH 19/19] Documentation/vm: add pin_user_pages.rst John Hubbard
2019-10-31 23:49   ` Ira Weiny
2019-10-31 23:53     ` John Hubbard
2019-11-01  0:48     ` John Hubbard
2019-11-03 19:53   ` John Hubbard

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