lkml.org 
[lkml]   [2016]   [Aug]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression
On Thu, Aug 11, 2016 at 01:35:00PM -0700, Linus Torvalds wrote:

> The thing is, iov_iter_copy_from_user_atomic() doesn't itself enforce
> non-blocking user accesses, it depends on the caller blocking page
> faults.

Huh? The very first thing it does is
char *kaddr = kmap_atomic(page), *p = kaddr + offset;

If _that_ does not disable pagefaults, we are very deep in shit. AFAICS,
all instances of that sucker do disable those, including the non-highmem
default (it's
static inline void *kmap_atomic(struct page *page)
{
preempt_disable();
pagefault_disable();
return page_address(page);
}
)

\
 
 \ /
  Last update: 2016-09-17 09:56    [W:0.092 / U:0.268 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site