On 21/02/18 14:01, Igor Stoppa wrote:
> it seems to return garbage also without this patch, but I need to clean
> up the code, try it again and possibly come up with a demo patch for
> triggering the problem.
>
> I'll investigate it more. However it doesn't seem to be related to the
> functionali
On 20/02/18 22:54, Matthew Wilcox wrote:
> On Tue, Feb 20, 2018 at 09:53:30PM +0200, Igor Stoppa wrote:
[...]
>> It was found while testing on a configuration with framebuffer.
>
> ... ah. You tried to use vmalloc_to_page() on something which wasn't
> backed by a struct page. That's *suppose
On Tue, Feb 20, 2018 at 09:53:30PM +0200, Igor Stoppa wrote:
> The patch relies on the function vmalloc_to_page ... which will return
> NULL when applied to huge mappings, while the original implementation
> will still work.
Huh? vmalloc_to_page() should work for huge mappings...
> It was found
On 12/02/18 18:24, Igor Stoppa wrote:
>
>
> On 11/02/18 23:16, Matthew Wilcox wrote:
>> On Sun, Feb 11, 2018 at 05:19:17AM +0200, Igor Stoppa wrote:
>>> The struct page has a "mapping" field, which can be re-used, to store a
>>> pointer to the parent area. This will avoid more expensive searche
When a page is used for virtual memory, it is often necessary to obtian
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area. This
On 11/02/18 23:16, Matthew Wilcox wrote:
> On Sun, Feb 11, 2018 at 05:19:17AM +0200, Igor Stoppa wrote:
>> The struct page has a "mapping" field, which can be re-used, to store a
>> pointer to the parent area. This will avoid more expensive searches.
>>
>> As example, the function find_vm_area is
On Sun, Feb 11, 2018 at 05:19:17AM +0200, Igor Stoppa wrote:
> The struct page has a "mapping" field, which can be re-used, to store a
> pointer to the parent area. This will avoid more expensive searches.
>
> As example, the function find_vm_area is reimplemented, to take advantage
> of the newly
When a page is used for virtual memory, it is often necessary to obtian
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area. This
On 06/02/18 14:37, Matthew Wilcox wrote:
[...]
> LOCAL variable names should be short, and to the point.
[...]
> (Documentation/process/coding-style.rst)
ok, will do, thanks for the pointer!
--
igor
On 05/02/18 17:33, Christopher Lameter wrote:
> On Sat, 3 Feb 2018, Igor Stoppa wrote:
>
>> - the property of the compound page will affect the property of all the
>> pages in the compound, so when one is write protected, it can generate a
>> lot of wasted memory, if there is too much slack (bec
On Tue, Jan 30, 2018 at 05:14:43PM +0200, Igor Stoppa wrote:
> @@ -1744,6 +1748,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned
> long align,
> const void *caller)
> {
> struct vm_struct *area;
> + unsigned int page_counter;
> void *addr;
>
On Sat, 3 Feb 2018, Igor Stoppa wrote:
> - the property of the compound page will affect the property of all the
> pages in the compound, so when one is write protected, it can generate a
> lot of wasted memory, if there is too much slack (because of the order)
> With vmalloc, I can allocate any n
When a page is used for virtual memory, it is often necessary to obtian
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area. This
When a page is used for virtual memory, it is often necessary to obtian
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area. This
On 02/02/18 20:43, Christopher Lameter wrote:
> On Thu, 1 Feb 2018, Igor Stoppa wrote:
>
>>> Would it not be better to use compound page allocations here?
[...]
> Ok its compound_head(). See also the use in the SLAB and SLUB allocator.
>
>> During hardened user copy permission check, I need t
On Thu, 1 Feb 2018, Igor Stoppa wrote:
> > Would it not be better to use compound page allocations here?
> > page_head(whatever) gets you the head page where you can store all sorts
> > of information about the chunk of memory.
>
> Can you please point me to this function/macro? I don't seem to be
On 01/02/18 23:11, Kees Cook wrote:
> IIUC, he means PageHead(), which is also hard to grep for, since it is
> a constructed name, via Page##uname in include/linux/page-flags.h:
>
> __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
Thank you, I'll try to provide a meaningful rep
On Thu, Feb 1, 2018 at 11:42 PM, Igor Stoppa wrote:
> On 01/02/18 02:00, Christopher Lameter wrote:
>> Would it not be better to use compound page allocations here?
>> page_head(whatever) gets you the head page where you can store all sorts
>> of information about the chunk of memory.
>
> Can you
On 01/02/18 02:00, Christopher Lameter wrote:
> On Tue, 30 Jan 2018, Igor Stoppa wrote:
>
>> @@ -1769,6 +1774,9 @@ void *__vmalloc_node_range(unsigned long size,
>> unsigned long align,
>>
>> kmemleak_vmalloc(area, size, gfp_mask);
>>
>> +for (page_counter = 0; page_counter < area->nr_
On Tue, 30 Jan 2018, Igor Stoppa wrote:
> @@ -1769,6 +1774,9 @@ void *__vmalloc_node_range(unsigned long size, unsigned
> long align,
>
> kmemleak_vmalloc(area, size, gfp_mask);
>
> + for (page_counter = 0; page_counter < area->nr_pages; page_counter++)
> + area->pages[page_
When a page is used for virtual memory, it is often necessary to obtian
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area. This
When a page is used for virtual memory, it is often necessary to obtian
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area. This
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