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SubjectRe: [PATCH 4.4 013/193] staging: android: ion: Add __GFP_NOWARN for system contig heap
On Fri, Feb 23, 2018 at 07:24:06PM +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Laura Abbott <labbott@redhat.com>
>
> commit 0c75f10312a35b149b2cebb1832316b35c2337ca upstream.
>
> syzbot reported a warning from Ion:
>
> WARNING: CPU: 1 PID: 3485 at mm/page_alloc.c:3926
>
> ...
> __alloc_pages_nodemask+0x9fb/0xd80 mm/page_alloc.c:4252
> alloc_pages_current+0xb6/0x1e0 mm/mempolicy.c:2036
> alloc_pages include/linux/gfp.h:492 [inline]
> ion_system_contig_heap_allocate+0x40/0x2c0
> drivers/staging/android/ion/ion_system_heap.c:374
> ion_buffer_create drivers/staging/android/ion/ion.c:93 [inline]
> ion_alloc+0x2c1/0x9e0 drivers/staging/android/ion/ion.c:420
> ion_ioctl+0x26d/0x380 drivers/staging/android/ion/ion-ioctl.c:84
> vfs_ioctl fs/ioctl.c:46 [inline]
> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
> SYSC_ioctl fs/ioctl.c:701 [inline]
> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>
> This is a warning about attempting to allocate order > MAX_ORDER. This
> is coming from a userspace Ion allocation request. Since userspace is
> free to request however much memory it wants (and the kernel is free to
> deny its allocation), silence the allocation attempt with __GFP_NOWARN
> in case it fails.
>
> Reported-by: syzbot+76e7efc4748495855a4d@syzkaller.appspotmail.com
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Signed-off-by: Laura Abbott <labbott@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> drivers/staging/android/ion/ion_system_heap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/drivers/staging/android/ion/ion_system_heap.c
> +++ b/drivers/staging/android/ion/ion_system_heap.c
> @@ -336,7 +336,7 @@ static int ion_system_contig_heap_alloca
> if (align > (PAGE_SIZE << order))
> return -EINVAL;
>
> - page = alloc_pages(low_order_gfp_flags, order);
> + page = alloc_pages(low_order_gfp_flags | __GFP_NOWARN, order);
> if (!page)
> return -ENOMEM;
>
>
>

This commit is not necessary as __GFP_NOWARN is still in the global
low_order_gfp_flags since commit d2805d7fff5b ("staging: ion: remove
__GFP_NOWARN when use low order gfp flags") did not show up until 4.9.
This also applies to 3.18.

Thanks!
Nathan

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