Messages in this thread | | | Date | Thu, 3 Feb 2022 06:01:36 -0800 | From | Christoph Hellwig <> | Subject | Re: [PATCH v3 4/4] mm/gup: remove get_user_pages_locked() |
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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.
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