Messages in this thread | | | Date | Thu, 3 Feb 2022 13:27:17 -0800 | Subject | Re: [PATCH v3 4/4] mm/gup: remove get_user_pages_locked() | From | John Hubbard <> |
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On 2/3/22 06:01, Christoph Hellwig wrote: > On Thu, Feb 03, 2022 at 01:32:32AM -0800, John Hubbard wrote: >> There is only one caller of get_user_pages_locked(). The purpose of >> get_user_pages_locked() is to allow for unlocking the mmap_lock when >> reading a page from the disk during a page fault (hidden behind >> VM_FAULT_RETRY). The idea is to reduce contention on the heavily-used >> mmap_lock. (Thanks to Jan Kara for clearly pointing that out, and in >> fact I've used some of his wording here.) >> >> However, it is unlikely for lookup_node() to take a page fault. With >> that in mind, change over to calling get_user_pages_fast(). This >> simplifies the code, runs a little faster in the expected case, and >> allows removing get_user_pages_locked() entirely. > > Maybe split the lookup_node changes into a separate patch, as that > allows to document that change even better.
OK, I'll do that.
thanks, -- John Hubbard NVIDIA
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