[PATCH v2] cifs: drop the incorrect assertion in cifs_swap_rw()

[PATCH v2] cifs: drop the incorrect assertion in cifs_swap_rw()

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

Since commit 2282679fb20b ("mm: submit multipage write for SWP_FS_OPS
swap-space"), we can plug multiple pages then unplug them all together.
That means iov_iter_count(iter) could be way bigger than PAGE_SIZE, it
actually equals the size of iov_iter_npages(iter, INT_MAX).

Note this issue has nothing to do with large folios as we don't support
THP_SWPOUT to non-block devices.

Fixes: 2282679fb20b ("mm: submit multipage write for SWP_FS_OPS swap-space")
Reported-by: Christoph Hellwig <hch@lst.de>
Closes: https://lore.kernel.org/linux-mm/20240614100329.1203579-1-hch@lst.de/
Cc: NeilBrown <neilb@suse.de>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Steve French <sfrench@samba.org>
Cc: Trond Myklebust <trondmy@kernel.org>
Cc: Chuanhua Han <hanchuanhua@oppo.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Paulo Alcantara <pc@manguebit.com>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 -v2:
 * drop the assertion instead of fixing the assertion.
   per the comments of Willy, Christoph in nfs thread.

 fs/smb/client/file.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 9d5c2440abfc..1e269e0bc75b 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -3200,8 +3200,6 @@ static int cifs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
 {
 	ssize_t ret;
 
-	WARN_ON_ONCE(iov_iter_count(iter) != PAGE_SIZE);
-
 	if (iov_iter_rw(iter) == READ)
 		ret = netfs_unbuffered_read_iter_locked(iocb, iter);
 	else
-- 
2.34.1

Re: [PATCH v2] cifs: drop the incorrect assertion in cifs_swap_rw()

[Steve French]

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tentatively merged into cifs-2.6.git for-next pending testing and any
additional review

On Tue, Jun 18, 2024 at 3:56 AM Barry Song <21cnbao@gmail.com> wrote:

> From: Barry Song <v-songbaohua@oppo.com>
>
> Since commit 2282679fb20b ("mm: submit multipage write for SWP_FS_OPS
> swap-space"), we can plug multiple pages then unplug them all together.
> That means iov_iter_count(iter) could be way bigger than PAGE_SIZE, it
> actually equals the size of iov_iter_npages(iter, INT_MAX).
>
> Note this issue has nothing to do with large folios as we don't support
> THP_SWPOUT to non-block devices.
>
> Fixes: 2282679fb20b ("mm: submit multipage write for SWP_FS_OPS
> swap-space")
> Reported-by: Christoph Hellwig <hch@lst.de>
> Closes:
> https://lore.kernel.org/linux-mm/20240614100329.1203579-1-hch@lst.de/
> Cc: NeilBrown <neilb@suse.de>
> Cc: Anna Schumaker <anna@kernel.org>
> Cc: Steve French <sfrench@samba.org>
> Cc: Trond Myklebust <trondmy@kernel.org>
> Cc: Chuanhua Han <hanchuanhua@oppo.com>
> Cc: Ryan Roberts <ryan.roberts@arm.com>
> Cc: Chris Li <chrisl@kernel.org>
> Cc: "Huang, Ying" <ying.huang@intel.com>
> Cc: Jeff Layton <jlayton@kernel.org>
> Cc: Paulo Alcantara <pc@manguebit.com>
> Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
> Cc: Shyam Prasad N <sprasad@microsoft.com>
> Cc: Tom Talpey <tom@talpey.com>
> Cc: Bharath SM <bharathsm@microsoft.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
>  -v2:
>  * drop the assertion instead of fixing the assertion.
>    per the comments of Willy, Christoph in nfs thread.
>
>  fs/smb/client/file.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
> index 9d5c2440abfc..1e269e0bc75b 100644
> --- a/fs/smb/client/file.c
> +++ b/fs/smb/client/file.c
> @@ -3200,8 +3200,6 @@ static int cifs_swap_rw(struct kiocb *iocb, struct
> iov_iter *iter)
>  {
>         ssize_t ret;
>
> -       WARN_ON_ONCE(iov_iter_count(iter) != PAGE_SIZE);
> -
>         if (iov_iter_rw(iter) == READ)
>                 ret = netfs_unbuffered_read_iter_locked(iocb, iter);
>         else
> --
> 2.34.1
>
>
>

-- 
Thanks,

Steve

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Re: [PATCH v2] cifs: drop the incorrect assertion in cifs_swap_rw()

[Barry Song]

On Wed, Jun 19, 2024 at 3:48 PM Steve French <smfrench@gmail.com> wrote:
>
> tentatively merged into cifs-2.6.git for-next pending testing and any additional review

Steve, Thanks! I guess you missed an email from mm-commits.

A couple of hours ago, this was pulled into mm-hotfixes-unstable, likely
for the same purpose. Will this cause any conflicts when both changes hit
linux-next?

https://lore.kernel.org/mm-commits/20240618195943.EC07BC3277B@smtp.kernel.org/

Will we just keep one?

>
> On Tue, Jun 18, 2024 at 3:56 AM Barry Song <21cnbao@gmail.com> wrote:
>>
>> From: Barry Song <v-songbaohua@oppo.com>
>>
>> Since commit 2282679fb20b ("mm: submit multipage write for SWP_FS_OPS
>> swap-space"), we can plug multiple pages then unplug them all together.
>> That means iov_iter_count(iter) could be way bigger than PAGE_SIZE, it
>> actually equals the size of iov_iter_npages(iter, INT_MAX).
>>
>> Note this issue has nothing to do with large folios as we don't support
>> THP_SWPOUT to non-block devices.
>>
>> Fixes: 2282679fb20b ("mm: submit multipage write for SWP_FS_OPS swap-space")
>> Reported-by: Christoph Hellwig <hch@lst.de>
>> Closes: https://lore.kernel.org/linux-mm/20240614100329.1203579-1-hch@lst.de/
>> Cc: NeilBrown <neilb@suse.de>
>> Cc: Anna Schumaker <anna@kernel.org>
>> Cc: Steve French <sfrench@samba.org>
>> Cc: Trond Myklebust <trondmy@kernel.org>
>> Cc: Chuanhua Han <hanchuanhua@oppo.com>
>> Cc: Ryan Roberts <ryan.roberts@arm.com>
>> Cc: Chris Li <chrisl@kernel.org>
>> Cc: "Huang, Ying" <ying.huang@intel.com>
>> Cc: Jeff Layton <jlayton@kernel.org>
>> Cc: Paulo Alcantara <pc@manguebit.com>
>> Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
>> Cc: Shyam Prasad N <sprasad@microsoft.com>
>> Cc: Tom Talpey <tom@talpey.com>
>> Cc: Bharath SM <bharathsm@microsoft.com>
>> Cc: <stable@vger.kernel.org>
>> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
>> ---
>>  -v2:
>>  * drop the assertion instead of fixing the assertion.
>>    per the comments of Willy, Christoph in nfs thread.
>>
>>  fs/smb/client/file.c | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
>> index 9d5c2440abfc..1e269e0bc75b 100644
>> --- a/fs/smb/client/file.c
>> +++ b/fs/smb/client/file.c
>> @@ -3200,8 +3200,6 @@ static int cifs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
>>  {
>>         ssize_t ret;
>>
>> -       WARN_ON_ONCE(iov_iter_count(iter) != PAGE_SIZE);
>> -
>>         if (iov_iter_rw(iter) == READ)
>>                 ret = netfs_unbuffered_read_iter_locked(iocb, iter);
>>         else
>> --
>> 2.34.1
>>
>>
>
>
> --
> Thanks,
>
> Steve

Re: [PATCH v2] cifs: drop the incorrect assertion in cifs_swap_rw()

[Andrew Morton]

On Wed, 19 Jun 2024 16:44:15 +1200 Barry Song <21cnbao@gmail.com> wrote:

> On Wed, Jun 19, 2024 at 3:48 PM Steve French <smfrench@gmail.com> wrote:
> >
> > tentatively merged into cifs-2.6.git for-next pending testing and any additional review
> 
> Steve, Thanks! I guess you missed an email from mm-commits.
> 
> A couple of hours ago, this was pulled into mm-hotfixes-unstable, likely
> for the same purpose. Will this cause any conflicts when both changes hit
> linux-next?
> 
> https://lore.kernel.org/mm-commits/20240618195943.EC07BC3277B@smtp.kernel.org/
> 
> Will we just keep one?

Either is OK, but I suggest a 6.10-rcX merge while retaining the cc:stable.

Re: [PATCH v2] cifs: drop the incorrect assertion in cifs_swap_rw()

[Steve French]

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On Wed, Jun 19, 2024 at 8:23 PM Andrew Morton <akpm@linux-foundation.org>
wrote:

> On Wed, 19 Jun 2024 16:44:15 +1200 Barry Song <21cnbao@gmail.com> wrote:
>
> > On Wed, Jun 19, 2024 at 3:48 PM Steve French <smfrench@gmail.com> wrote:
> > >
> > > tentatively merged into cifs-2.6.git for-next pending testing and any
> additional review
> >
> > Steve, Thanks! I guess you missed an email from mm-commits.
> >
> > A couple of hours ago, this was pulled into mm-hotfixes-unstable, likely
> > for the same purpose. Will this cause any conflicts when both changes hit
> > linux-next?
> >
> >
> https://lore.kernel.org/mm-commits/20240618195943.EC07BC3277B@smtp.kernel.org/
> >
> > Will we just keep one?
>
> Either is OK, but I suggest a 6.10-rcX merge while retaining the cc:stable.
>

I have at least two cifs.ko patches to submit in a few days upstream, so am
fine with submitting the patch if it tests out ok tomorrow.

git.samba.org - sfrench/cifs-2.6.git/commit
<https://git.samba.org/?p=sfrench/cifs-2.6.git;a=commit;h=29433a17a79caa8680b9c0761f2b10502fda9ce3>
-- 
Thanks,

Steve

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