Re: [PATCH v2 2/5] userfaultfd: non-cooperative: add event for memory unmaps
From: Mike Rapoport <hidden>
Date: 2017-02-01 06:37:59
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On Tue, Jan 31, 2017 at 04:39:28PM -0800, Andrew Morton wrote:
On Fri, 27 Jan 2017 20:44:30 +0200 Mike Rapoport [off-list ref] wrote:quoted
When a non-cooperative userfaultfd monitor copies pages in the background, it may encounter regions that were already unmapped. Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely changes in the virtual memory layout. Since there might be different uffd contexts for the affected VMAs, we first should create a temporary representation for the unmap event for each uffd context and then notify them one by one to the appropriate userfault file descriptors. The event notification occurs after the mmap_sem has been released.I was going to bug you about not updating Documentation/vm/userfaultfd.txt but the UFFD_FEATURE flags aren't documented?
I'm going to send the documentation update in the next few days. -- Sincerely yours, Mike. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>