lkml.org 
[lkml]   [2022]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 4/4] mm/gup: remove get_user_pages_locked()
    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.

    \
     
     \ /
      Last update: 2022-02-03 15:02    [W:4.823 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site