* [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails
@ 2019-03-25 8:13 Yue Hu
2019-03-25 10:14 ` Anshuman Khandual
2019-03-25 22:15 ` Andrew Morton
0 siblings, 2 replies; 4+ messages in thread
From: Yue Hu @ 2019-03-25 8:13 UTC (permalink / raw)
To: akpm, iamjoonsoo.kim, labbott, rppt, rdunlap; +Cc: linux-mm, huyue2
From: Yue Hu <huyue2@yulong.com>
A previous commit f022d8cb7ec7 ("mm: cma: Don't crash on allocation
if CMA area can't be activated") fixes the crash issue when activation
fails via setting cma->count as 0, same logic exists if bitmap
allocation fails.
Signed-off-by: Yue Hu <huyue2@yulong.com>
---
mm/cma.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/cma.c b/mm/cma.c
index f5bf819..991a6ce 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -106,8 +106,10 @@ static int __init cma_activate_area(struct cma *cma)
cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
- if (!cma->bitmap)
+ if (!cma->bitmap) {
+ cma->count = 0;
return -ENOMEM;
+ }
WARN_ON_ONCE(!pfn_valid(pfn));
zone = page_zone(pfn_to_page(pfn));
--
1.9.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails
2019-03-25 8:13 [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails Yue Hu
@ 2019-03-25 10:14 ` Anshuman Khandual
2019-03-25 22:15 ` Andrew Morton
1 sibling, 0 replies; 4+ messages in thread
From: Anshuman Khandual @ 2019-03-25 10:14 UTC (permalink / raw)
To: Yue Hu, akpm, iamjoonsoo.kim, labbott, rppt, rdunlap; +Cc: linux-mm, huyue2
On 03/25/2019 01:43 PM, Yue Hu wrote:
> From: Yue Hu <huyue2@yulong.com>
>
> A previous commit f022d8cb7ec7 ("mm: cma: Don't crash on allocation
> if CMA area can't be activated") fixes the crash issue when activation
> fails via setting cma->count as 0, same logic exists if bitmap
> allocation fails.
>
> Signed-off-by: Yue Hu <huyue2@yulong.com>
Looks good to me. Just wondering if cma->count = 0 should be wrapped around in
a helper which explicitly states that this cma cannot be used for allocation.
Nonetheless.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails
2019-03-25 8:13 [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails Yue Hu
2019-03-25 10:14 ` Anshuman Khandual
@ 2019-03-25 22:15 ` Andrew Morton
2019-03-26 1:59 ` Yue Hu
1 sibling, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2019-03-25 22:15 UTC (permalink / raw)
To: Yue Hu
Cc: iamjoonsoo.kim, labbott, rppt, rdunlap, linux-mm, huyue2,
Anshuman Khandual
On Mon, 25 Mar 2019 16:13:09 +0800 Yue Hu <zbestahu@gmail.com> wrote:
> From: Yue Hu <huyue2@yulong.com>
>
> A previous commit f022d8cb7ec7 ("mm: cma: Don't crash on allocation
> if CMA area can't be activated") fixes the crash issue when activation
> fails via setting cma->count as 0, same logic exists if bitmap
> allocation fails.
>
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -106,8 +106,10 @@ static int __init cma_activate_area(struct cma *cma)
>
> cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
>
> - if (!cma->bitmap)
> + if (!cma->bitmap) {
> + cma->count = 0;
> return -ENOMEM;
> + }
>
> WARN_ON_ONCE(!pfn_valid(pfn));
> zone = page_zone(pfn_to_page(pfn));
I'm unsure whether this is needed.
kmalloc() within __init code is generally considered to be a "can't
fail".
If this was the only issue then I guess I'd take the patch if only for
documentation/clarity purposes. But cma_areas[] is in bss and is
guaranteed to be all-zeroes, so I suspect this bug is a can't-happen.
And we could revert f022d8cb7ec7 if we could be bothered (I can't).
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails
2019-03-25 22:15 ` Andrew Morton
@ 2019-03-26 1:59 ` Yue Hu
0 siblings, 0 replies; 4+ messages in thread
From: Yue Hu @ 2019-03-26 1:59 UTC (permalink / raw)
To: Andrew Morton
Cc: iamjoonsoo.kim, labbott, rppt, rdunlap, linux-mm, huyue2,
Anshuman Khandual
On Mon, 25 Mar 2019 15:15:41 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> On Mon, 25 Mar 2019 16:13:09 +0800 Yue Hu <zbestahu@gmail.com> wrote:
>
> > From: Yue Hu <huyue2@yulong.com>
> >
> > A previous commit f022d8cb7ec7 ("mm: cma: Don't crash on allocation
> > if CMA area can't be activated") fixes the crash issue when activation
> > fails via setting cma->count as 0, same logic exists if bitmap
> > allocation fails.
> >
> > --- a/mm/cma.c
> > +++ b/mm/cma.c
> > @@ -106,8 +106,10 @@ static int __init cma_activate_area(struct cma *cma)
> >
> > cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
> >
> > - if (!cma->bitmap)
> > + if (!cma->bitmap) {
> > + cma->count = 0;
> > return -ENOMEM;
> > + }
> >
> > WARN_ON_ONCE(!pfn_valid(pfn));
> > zone = page_zone(pfn_to_page(pfn));
>
> I'm unsure whether this is needed.
>
> kmalloc() within __init code is generally considered to be a "can't
> fail".
>
> If this was the only issue then I guess I'd take the patch if only for
> documentation/clarity purposes. But cma_areas[] is in bss and is
> guaranteed to be all-zeroes, so I suspect this bug is a can't-happen.
However, firstly cma->count will be assigned to size >> PAGE_SHIFT in
cma_init_reserved_mem().
> And we could revert f022d8cb7ec7 if we could be bothered (I can't).
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-03-26 1:59 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-03-25 8:13 [PATCH] mm/cma: Fix crash on CMA allocation if bitmap allocation fails Yue Hu
2019-03-25 10:14 ` Anshuman Khandual
2019-03-25 22:15 ` Andrew Morton
2019-03-26 1:59 ` Yue Hu
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