* [PATCH] relay: use kvcalloc to alloc page array in relay_alloc_page_array
@ 2022-09-09 10:10 wuchi
2022-09-09 21:48 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: wuchi @ 2022-09-09 10:10 UTC (permalink / raw)
To: hch, axboe, akpm; +Cc: linux-kernel
The kvcalloc is safer because it will check the integer overflows,
and using it will simple the logic of allocation size.
Signed-off-by: wuchi <wuchi.zero@gmail.com>
---
kernel/relay.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/kernel/relay.c b/kernel/relay.c
index 6a611e779e95..d7edc934c56d 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -60,10 +60,7 @@ static const struct vm_operations_struct relay_file_mmap_ops = {
*/
static struct page **relay_alloc_page_array(unsigned int n_pages)
{
- const size_t pa_size = n_pages * sizeof(struct page *);
- if (pa_size > PAGE_SIZE)
- return vzalloc(pa_size);
- return kzalloc(pa_size, GFP_KERNEL);
+ return kvcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
}
/*
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] relay: use kvcalloc to alloc page array in relay_alloc_page_array
2022-09-09 10:10 [PATCH] relay: use kvcalloc to alloc page array in relay_alloc_page_array wuchi
@ 2022-09-09 21:48 ` Andrew Morton
2022-09-10 14:24 ` chi wu
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2022-09-09 21:48 UTC (permalink / raw)
To: wuchi; +Cc: hch, axboe, linux-kernel
On Fri, 9 Sep 2022 18:10:25 +0800 wuchi <wuchi.zero@gmail.com> wrote:
> The kvcalloc is safer because it will check the integer overflows,
> and using it will simple the logic of allocation size.
>
> ...
>
> --- a/kernel/relay.c
> +++ b/kernel/relay.c
> @@ -60,10 +60,7 @@ static const struct vm_operations_struct relay_file_mmap_ops = {
> */
> static struct page **relay_alloc_page_array(unsigned int n_pages)
> {
> - const size_t pa_size = n_pages * sizeof(struct page *);
> - if (pa_size > PAGE_SIZE)
> - return vzalloc(pa_size);
> - return kzalloc(pa_size, GFP_KERNEL);
> + return kvcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> }
It isn't really equivalent because kvcalloc() may attempt a large
kmalloc() request, whereas the current relay_alloc_page_array()
implementation avoids this by choosing vmalloc() instead.
But I doubt if it matters - kvcalloc()->kvmalloc_node() does take some
care to prevent that large kmalloc() request from being too disruptive.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] relay: use kvcalloc to alloc page array in relay_alloc_page_array
2022-09-09 21:48 ` Andrew Morton
@ 2022-09-10 14:24 ` chi wu
0 siblings, 0 replies; 3+ messages in thread
From: chi wu @ 2022-09-10 14:24 UTC (permalink / raw)
To: Andrew Morton; +Cc: hch, axboe, linux-kernel
Andrew Morton <akpm@linux-foundation.org> 于2022年9月10日周六 05:48写道：
>
> On Fri, 9 Sep 2022 18:10:25 +0800 wuchi <wuchi.zero@gmail.com> wrote:
>
> > The kvcalloc is safer because it will check the integer overflows,
> > and using it will simple the logic of allocation size.
> >
> > ...
> >
> > --- a/kernel/relay.c
> > +++ b/kernel/relay.c
> > @@ -60,10 +60,7 @@ static const struct vm_operations_struct relay_file_mmap_ops = {
> > */
> > static struct page **relay_alloc_page_array(unsigned int n_pages)
> > {
> > - const size_t pa_size = n_pages * sizeof(struct page *);
> > - if (pa_size > PAGE_SIZE)
> > - return vzalloc(pa_size);
> > - return kzalloc(pa_size, GFP_KERNEL);
> > + return kvcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
> > }
>
> It isn't really equivalent because kvcalloc() may attempt a large
> kmalloc() request, whereas the current relay_alloc_page_array()
> implementation avoids this by choosing vmalloc() instead.
>
> But I doubt if it matters - kvcalloc()->kvmalloc_node() does take some
> care to prevent that large kmalloc() request from being too disruptive.
>
Thanks very much，got it.
^ permalink raw reply [flat|nested] 3+ messages in thread
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