Hi Andrew and all,
Here's another gup-to-pup (get_user_pages() to pin_user_pages())
conversion patch, this time from Leon Romanovsky, that we agreed is
better suited for the linux-mm tree than for linux-rdma. And it also
couldn't be merged until now (5.6-rc1) because it relies on stuff from
a few different git trees.
(Leon: I added my standard blurb about "this changes set_page_dirty() to
set_page_dirty_lock()", to the commit description.)
I've reviewed this, and done some basic checks (cross-compiles, and
a subset of an LTP run on x86), but I have not personally done directed
tests that would provide coverage of this change.
For that, could we please get some Tested-by tags, and any other tags
(reviews, acks) from those of you who have reportedly tested this? That
would be Hans or Santosh (on Cc below), I'm told:
Cc: Hans Westgaard Ry <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Leon Romanovsky (1):
net/rds: Track user mapped pages through special API
net/rds/rdma.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
base-commit: 359c92c02bfae1a6f1e8e37c298e518fd256642c
--
2.25.0
From: Leon Romanovsky <[email protected]>
Convert net/rds to use the newly introduces pin_user_pages() API,
which properly sets FOLL_PIN. Setting FOLL_PIN is now required for
code that requires tracking of pinned pages.
Note that this effectively changes the code's behavior: it now
ultimately calls set_page_dirty_lock(), instead of set_page_dirty().
This is probably more accurate.
As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]
[1] https://lore.kernel.org/r/[email protected]
Cc: Hans Westgaard Ry <[email protected]>
Cc: Santosh Shilimkar <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: John Hubbard <[email protected]>
---
net/rds/rdma.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/net/rds/rdma.c b/net/rds/rdma.c
index 3341eee87bf9..585e6b3b69ce 100644
--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -162,10 +162,9 @@ static int rds_pin_pages(unsigned long user_addr, unsigned int nr_pages,
if (write)
gup_flags |= FOLL_WRITE;
- ret = get_user_pages_fast(user_addr, nr_pages, gup_flags, pages);
+ ret = pin_user_pages_fast(user_addr, nr_pages, gup_flags, pages);
if (ret >= 0 && ret < nr_pages) {
- while (ret--)
- put_page(pages[ret]);
+ unpin_user_pages(pages, ret);
ret = -EFAULT;
}
@@ -300,8 +299,7 @@ static int __rds_rdma_map(struct rds_sock *rs, struct rds_get_mr_args *args,
* to release anything.
*/
if (!need_odp) {
- for (i = 0 ; i < nents; i++)
- put_page(sg_page(&sg[i]));
+ unpin_user_pages(pages, nr_pages);
kfree(sg);
}
ret = PTR_ERR(trans_private);
@@ -325,7 +323,12 @@ static int __rds_rdma_map(struct rds_sock *rs, struct rds_get_mr_args *args,
if (cookie_ret)
*cookie_ret = cookie;
- if (args->cookie_addr && put_user(cookie, (u64 __user *)(unsigned long) args->cookie_addr)) {
+ if (args->cookie_addr &&
+ put_user(cookie, (u64 __user *)(unsigned long)args->cookie_addr)) {
+ if (!need_odp) {
+ unpin_user_pages(pages, nr_pages);
+ kfree(sg);
+ }
ret = -EFAULT;
goto out;
}
@@ -496,9 +499,7 @@ void rds_rdma_free_op(struct rm_rdma_op *ro)
* is the case for a RDMA_READ which copies from remote
* to local memory
*/
- if (!ro->op_write)
- set_page_dirty(page);
- put_page(page);
+ unpin_user_pages_dirty_lock(&page, 1, !ro->op_write);
}
}
@@ -515,8 +516,7 @@ void rds_atomic_free_op(struct rm_atomic_op *ao)
/* Mark page dirty if it was possibly modified, which
* is the case for a RDMA_READ which copies from remote
* to local memory */
- set_page_dirty(page);
- put_page(page);
+ unpin_user_pages_dirty_lock(&page, 1, true);
kfree(ao->op_notifier);
ao->op_notifier = NULL;
@@ -944,7 +944,7 @@ int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
return ret;
err:
if (page)
- put_page(page);
+ unpin_user_page(page);
rm->atomic.op_active = 0;
kfree(rm->atomic.op_notifier);
--
2.25.0
On 2/11/20 7:03 PM, John Hubbard wrote:
> From: Leon Romanovsky <[email protected]>
>
> Convert net/rds to use the newly introduces pin_user_pages() API,
> which properly sets FOLL_PIN. Setting FOLL_PIN is now required for
> code that requires tracking of pinned pages.
>
> Note that this effectively changes the code's behavior: it now
> ultimately calls set_page_dirty_lock(), instead of set_page_dirty().
> This is probably more accurate.
>
> As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
> dealing with a file backed page where we have reference on the inode it
> hangs off." [1]
>
> [1] https://urldefense.com/v3/__https://lore.kernel.org/r/[email protected]__;!!GqivPVa7Brio!OJHuecs9Iup5ig3kQBi_423uMMuskWhBQAdOICrY3UQ_ZfEaxt9ySY7E8y32Q7pk5tByyA$
>
> Cc: Hans Westgaard Ry <[email protected]>
> Cc: Santosh Shilimkar <[email protected]>
> Signed-off-by: Leon Romanovsky <[email protected]>
> Signed-off-by: John Hubbard <[email protected]>
> ---
Change looks fine to me. Just on safer side, we will try
to test this change with regression suite to make sure it
works as expected.
For patch itself,
Acked-by: Santosh Shilimkar <[email protected]>
On Wed, Feb 12, 2020 at 09:31:51AM -0800, [email protected] wrote:
> On 2/11/20 7:03 PM, John Hubbard wrote:
> > From: Leon Romanovsky <[email protected]>
> >
> > Convert net/rds to use the newly introduces pin_user_pages() API,
> > which properly sets FOLL_PIN. Setting FOLL_PIN is now required for
> > code that requires tracking of pinned pages.
> >
> > Note that this effectively changes the code's behavior: it now
> > ultimately calls set_page_dirty_lock(), instead of set_page_dirty().
> > This is probably more accurate.
> >
> > As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
> > dealing with a file backed page where we have reference on the inode it
> > hangs off." [1]
> >
> > [1] https://urldefense.com/v3/__https://lore.kernel.org/r/[email protected]__;!!GqivPVa7Brio!OJHuecs9Iup5ig3kQBi_423uMMuskWhBQAdOICrY3UQ_ZfEaxt9ySY7E8y32Q7pk5tByyA$
> >
> > Cc: Hans Westgaard Ry <[email protected]>
> > Cc: Santosh Shilimkar <[email protected]>
> > Signed-off-by: Leon Romanovsky <[email protected]>
> > Signed-off-by: John Hubbard <[email protected]>
> > ---
> Change looks fine to me. Just on safer side, we will try
> to test this change with regression suite to make sure it
> works as expected.
Thanks Santosh,
I wrote this patch before John's series was merged into the tree,
but back then, Hans tested it and it worked, hope that it still works. :)
>
> For patch itself,
>
> Acked-by: Santosh Shilimkar <[email protected]>
>
On 2/12/20 9:51 AM, Leon Romanovsky wrote:
> On Wed, Feb 12, 2020 at 09:31:51AM -0800, [email protected] wrote:
>> On 2/11/20 7:03 PM, John Hubbard wrote:
>>> From: Leon Romanovsky <[email protected]>
>>>
>>> Convert net/rds to use the newly introduces pin_user_pages() API,
>>> which properly sets FOLL_PIN. Setting FOLL_PIN is now required for
>>> code that requires tracking of pinned pages.
>>>
>>> Note that this effectively changes the code's behavior: it now
>>> ultimately calls set_page_dirty_lock(), instead of set_page_dirty().
>>> This is probably more accurate.
>>>
>>> As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
>>> dealing with a file backed page where we have reference on the inode it
>>> hangs off." [1]
>>>
>>> [1] https://urldefense.com/v3/__https://lore.kernel.org/r/[email protected]__;!!GqivPVa7Brio!OJHuecs9Iup5ig3kQBi_423uMMuskWhBQAdOICrY3UQ_ZfEaxt9ySY7E8y32Q7pk5tByyA$
>>>
>>> Cc: Hans Westgaard Ry <[email protected]>
>>> Cc: Santosh Shilimkar <[email protected]>
>>> Signed-off-by: Leon Romanovsky <[email protected]>
>>> Signed-off-by: John Hubbard <[email protected]>
>>> ---
>> Change looks fine to me. Just on safer side, we will try
>> to test this change with regression suite to make sure it
>> works as expected.
>
> Thanks Santosh,
> I wrote this patch before John's series was merged into the tree,
> but back then, Hans tested it and it worked, hope that it still works. :)
>
I see. Wasn't aware of it. In that case, its should be fine.
Regards,
Santosh
From: John Hubbard <[email protected]>
Date: Tue, 11 Feb 2020 19:03:55 -0800
> From: Leon Romanovsky <[email protected]>
>
> Convert net/rds to use the newly introduces pin_user_pages() API,
> which properly sets FOLL_PIN. Setting FOLL_PIN is now required for
> code that requires tracking of pinned pages.
>
> Note that this effectively changes the code's behavior: it now
> ultimately calls set_page_dirty_lock(), instead of set_page_dirty().
> This is probably more accurate.
>
> As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
> dealing with a file backed page where we have reference on the inode it
> hangs off." [1]
>
> [1] https://lore.kernel.org/r/[email protected]
>
> Cc: Hans Westgaard Ry <[email protected]>
> Cc: Santosh Shilimkar <[email protected]>
> Signed-off-by: Leon Romanovsky <[email protected]>
> Signed-off-by: John Hubbard <[email protected]>
Applied, thank you.