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From: Souptick Joarder <jrdr.linux@gmail.com>
To: Ralph Campbell <rcampbell@nvidia.com>
Cc: Linux-MM <linux-mm@kvack.org>,
	linux-kernel@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Balbir Singh <bsingharora@gmail.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Matthew Wilcox <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 4/5] mm/hmm: hmm_vma_fault() doesn't always call hmm_range_unregister()
Date: Tue, 7 May 2019 18:45:54 +0530	[thread overview]
Message-ID: <CAFqt6zbhLQuw2N5-=Nma-vHz1BkWjviOttRsPXmde8U1Oocz0Q@mail.gmail.com> (raw)
In-Reply-To: <20190506232942.12623-5-rcampbell@nvidia.com>

On Tue, May 7, 2019 at 5:00 AM <rcampbell@nvidia.com> wrote:
>
> From: Ralph Campbell <rcampbell@nvidia.com>
>
> The helper function hmm_vma_fault() calls hmm_range_register() but is
> missing a call to hmm_range_unregister() in one of the error paths.
> This leads to a reference count leak and ultimately a memory leak on
> struct hmm.
>
> Always call hmm_range_unregister() if hmm_range_register() succeeded.

How about * Call hmm_range_unregister() in error path if
hmm_range_register() succeeded* ?

>
> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Balbir Singh <bsingharora@gmail.com>
> Cc: Dan Carpenter <dan.carpenter@oracle.com>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Souptick Joarder <jrdr.linux@gmail.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
>  include/linux/hmm.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 35a429621e1e..fa0671d67269 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -559,6 +559,7 @@ static inline int hmm_vma_fault(struct hmm_range *range, bool block)
>                 return (int)ret;
>
>         if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {
> +               hmm_range_unregister(range);
>                 /*
>                  * The mmap_sem was taken by driver we release it here and
>                  * returns -EAGAIN which correspond to mmap_sem have been
> @@ -570,13 +571,13 @@ static inline int hmm_vma_fault(struct hmm_range *range, bool block)
>
>         ret = hmm_range_fault(range, block);
>         if (ret <= 0) {
> +               hmm_range_unregister(range);

what is the reason to moved it up ?

>                 if (ret == -EBUSY || !ret) {
>                         /* Same as above, drop mmap_sem to match old API. */
>                         up_read(&range->vma->vm_mm->mmap_sem);
>                         ret = -EBUSY;
>                 } else if (ret == -EAGAIN)
>                         ret = -EBUSY;
> -               hmm_range_unregister(range);
>                 return ret;
>         }
>         return 0;
> --
> 2.20.1
>

  reply	other threads:[~2019-05-07 13:16 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-06 23:29 [PATCH 0/5] mm/hmm: HMM documentation updates and code fixes rcampbell
2019-05-06 23:29 ` [PATCH 1/5] mm/hmm: Update HMM documentation rcampbell
2019-06-06 14:02   ` Jason Gunthorpe
2019-06-06 18:50     ` Ralph Campbell
2019-06-06 19:32       ` Jason Gunthorpe
2019-05-06 23:29 ` [PATCH 2/5] mm/hmm: Clean up some coding style and comments rcampbell
2019-06-06 14:16   ` Jason Gunthorpe
2019-06-06 14:27     ` Jerome Glisse
2019-06-06 15:41       ` Jason Gunthorpe
2019-06-06 15:52         ` Jerome Glisse
2019-06-06 16:55           ` Joe Perches
2019-06-06 18:54           ` Jason Gunthorpe
2019-06-06 15:57   ` Jason Gunthorpe
2019-06-07  0:44     ` Ralph Campbell
2019-05-06 23:29 ` [PATCH 3/5] mm/hmm: Use mm_get_hmm() in hmm_range_register() rcampbell
2019-05-23 12:51   ` Jason Gunthorpe
2019-05-23 18:19     ` Ralph Campbell
2019-05-23 18:46     ` John Hubbard
2019-05-06 23:29 ` [PATCH 4/5] mm/hmm: hmm_vma_fault() doesn't always call hmm_range_unregister() rcampbell
2019-05-07 13:15   ` Souptick Joarder [this message]
2019-05-07 18:12     ` Ralph Campbell
2019-05-09  4:42       ` Souptick Joarder
2019-05-12 15:07       ` Jerome Glisse
2019-05-12 15:28         ` Jerome Glisse
2019-05-13 17:23         ` Ralph Campbell
2019-06-06 14:50   ` Jason Gunthorpe
2019-06-06 19:44     ` Ralph Campbell
2019-06-06 19:54       ` Jason Gunthorpe
2019-06-06 21:08         ` Ralph Campbell
2019-05-12 15:08 ` [PATCH 0/5] mm/hmm: HMM documentation updates and code fixes Jerome Glisse
2019-05-13 17:26   ` Ralph Campbell
2019-05-13 18:10     ` Jerome Glisse
2019-06-06 14:53 ` Jason Gunthorpe

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