Messages in this thread | | | Date | Thu, 11 Aug 2016 23:16:35 +0100 | From | Al Viro <> | Subject | Re: [LKP] [lkp] [xfs] 68a9f5e700: aim7.jobs-per-min -13.6% regression |
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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); } )
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