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From: Minchan Kim <minchan@kernel.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: linaro-mm-sig@lists.linaro.org, orjan.eide@arm.com,
	sspatil@google.com, christian.koenig@amd.com,
	kernel-team@android.com, jajones@nvidia.com,
	linux-kernel@vger.kernel.org, lmark@codeaurora.org,
	hch@infradead.org, linux-mm@kvack.org,
	dri-devel@lists.freedesktop.org, cgoldswo@codeaurora.org,
	hridya@google.com, akpm@linux-foundation.org, labbott@redhat.com,
	robin.murphy@arm.com, linux-media@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error
Date: Tue, 2 Feb 2021 17:31:03 -0800	[thread overview]
Message-ID: <YBn81xAeCqHgudYb@google.com> (raw)
In-Reply-To: <20210203003134.2422308-1-surenb@google.com>

On Tue, Feb 02, 2021 at 04:31:33PM -0800, Suren Baghdasaryan wrote:
> Replace BUG_ON(vma->vm_flags & VM_PFNMAP) in vm_insert_page with
> WARN_ON_ONCE and returning an error. This is to ensure users of the
> vm_insert_page that set VM_PFNMAP are notified of the wrong flag usage
> and get an indication of an error without panicing the kernel.
> This will help identifying drivers that need to clear VM_PFNMAP before
> using dmabuf system heap which is moving to use vm_insert_page.
> 
> Suggested-by: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  mm/memory.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index feff48e1465a..e503c9801cd9 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1827,7 +1827,8 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
>  		return -EINVAL;
>  	if (!(vma->vm_flags & VM_MIXEDMAP)) {
>  		BUG_ON(mmap_read_trylock(vma->vm_mm));

Better to replace above BUG_ON with WARN_ON_ONCE, too?
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WARNING: multiple messages have this Message-ID (diff)
From: Minchan Kim <minchan@kernel.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: sumit.semwal@linaro.org, akpm@linux-foundation.org,
	hch@infradead.org, lmark@codeaurora.org, labbott@redhat.com,
	Brian.Starkey@arm.com, john.stultz@linaro.org,
	christian.koenig@amd.com, cgoldswo@codeaurora.org,
	orjan.eide@arm.com, robin.murphy@arm.com, jajones@nvidia.com,
	hridya@google.com, sspatil@google.com,
	linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, kernel-team@android.com
Subject: Re: [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error
Date: Tue, 2 Feb 2021 17:31:03 -0800	[thread overview]
Message-ID: <YBn81xAeCqHgudYb@google.com> (raw)
In-Reply-To: <20210203003134.2422308-1-surenb@google.com>

On Tue, Feb 02, 2021 at 04:31:33PM -0800, Suren Baghdasaryan wrote:
> Replace BUG_ON(vma->vm_flags & VM_PFNMAP) in vm_insert_page with
> WARN_ON_ONCE and returning an error. This is to ensure users of the
> vm_insert_page that set VM_PFNMAP are notified of the wrong flag usage
> and get an indication of an error without panicing the kernel.
> This will help identifying drivers that need to clear VM_PFNMAP before
> using dmabuf system heap which is moving to use vm_insert_page.
> 
> Suggested-by: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  mm/memory.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index feff48e1465a..e503c9801cd9 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1827,7 +1827,8 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
>  		return -EINVAL;
>  	if (!(vma->vm_flags & VM_MIXEDMAP)) {
>  		BUG_ON(mmap_read_trylock(vma->vm_mm));

Better to replace above BUG_ON with WARN_ON_ONCE, too?

  parent reply	other threads:[~2021-02-03  1:31 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-03  0:31 [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error Suren Baghdasaryan
2021-02-03  0:31 ` Suren Baghdasaryan
2021-02-03  0:31 ` [PATCH v2 2/2] dma-buf: heaps: Map system heap pages as managed by linux vm Suren Baghdasaryan
2021-02-03  0:31   ` Suren Baghdasaryan
2021-02-03  1:39   ` Minchan Kim
2021-02-03  1:39     ` Minchan Kim
2021-02-03  2:02     ` Suren Baghdasaryan
2021-02-03  2:02       ` Suren Baghdasaryan
2021-02-03  8:05       ` Christian König
2021-02-03  8:05         ` Christian König
2021-02-03 19:53         ` Suren Baghdasaryan
2021-02-03 19:53           ` Suren Baghdasaryan
2021-02-03  2:07   ` John Stultz
2021-02-03  2:07     ` John Stultz
2021-02-03  2:13     ` Suren Baghdasaryan
2021-02-03  2:13       ` Suren Baghdasaryan
2021-02-03  1:27 ` [PATCH 1/2] mm: replace BUG_ON in vm_insert_page with a return of an error Miaohe Lin
2021-02-03  1:27   ` Miaohe Lin
2021-02-03  1:31 ` Minchan Kim [this message]
2021-02-03  1:31   ` Minchan Kim
2021-02-03  1:55   ` Suren Baghdasaryan
2021-02-03  1:55     ` Suren Baghdasaryan
2021-02-03  1:55 ` Matthew Wilcox
2021-02-03  1:55   ` Matthew Wilcox
2021-02-03  2:26   ` Suren Baghdasaryan
2021-02-03  2:26     ` Suren Baghdasaryan
2021-02-03  8:52   ` [Linaro-mm-sig] " Daniel Vetter
2021-02-03  8:52     ` Daniel Vetter
2021-02-03 20:20     ` Suren Baghdasaryan
2021-02-03 20:20       ` Suren Baghdasaryan
2021-02-03 20:29       ` Daniel Vetter
2021-02-03 20:29         ` Daniel Vetter
2021-02-03 21:25         ` Daniel Vetter
2021-02-03 21:25           ` Daniel Vetter
2021-02-03 21:41           ` Suren Baghdasaryan
2021-02-03 21:41             ` Suren Baghdasaryan
2021-02-04  8:16             ` Christian König
2021-02-04  8:16               ` Christian König
2021-02-04 15:22               ` Daniel Vetter
2021-02-04 15:22                 ` Daniel Vetter
2021-02-04 15:54               ` Alex Deucher
2021-02-04 15:54                 ` Alex Deucher
2021-02-05  3:39                 ` Suren Baghdasaryan
2021-02-05  3:39                   ` Suren Baghdasaryan
2021-02-04  7:53       ` Christian König
2021-02-04  7:53         ` Christian König

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