Messages in this thread Patch in this message | | | Date | Thu, 1 Nov 2018 14:47:23 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v4] mm/page_owner: clamp read count to PAGE_SIZE |
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On Fri, 2 Nov 2018 01:00:07 +0800 <miles.chen@mediatek.com> wrote:
> From: Miles Chen <miles.chen@mediatek.com> > > The page owner read might allocate a large size of memory with > a large read count. Allocation fails can easily occur when doing > high order allocations. > > Clamp buffer size to PAGE_SIZE to avoid arbitrary size allocation > and avoid allocation fails due to high order allocation. > > ... > > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -351,6 +351,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, > .skip = 0 > }; > > + count = count > PAGE_SIZE ? PAGE_SIZE : count; > kbuf = kmalloc(count, GFP_KERNEL); > if (!kbuf) > return -ENOMEM;
A bit tidier:
--- a/mm/page_owner.c~mm-page_owner-clamp-read-count-to-page_size-fix +++ a/mm/page_owner.c @@ -351,7 +351,7 @@ print_page_owner(char __user *buf, size_ .skip = 0 }; - count = count > PAGE_SIZE ? PAGE_SIZE : count; + count = min_t(size_t, count, PAGE_SIZE); kbuf = kmalloc(count, GFP_KERNEL); if (!kbuf) return -ENOMEM;
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