On 2021/4/15 0:13, Tim Chen wrote: > > > On 4/13/21 6:04 PM, Huang, Ying wrote: >> Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> writes: >> >>> On 4/12/21 6:27 PM, Huang, Ying wrote: >>> >>>> >>>> This isn't the commit that introduces the race. You can use `git blame` >>>> find out the correct commit. For this it's commit 0bcac06f27d7 "mm, >>>> swap: skip swapcache for swapin of synchronous device". >>>> >>>> And I suggest to merge 1/5 and 2/5 to make it easy to get the full >>>> picture. >>> >>> I'll suggest make fix to do_swap_page race with get/put_swap_device >>> as a first patch. Then the per_cpu_ref stuff in patch 1 and patch 2 can >>> be combined together. >> >> The original get/put_swap_device() use rcu_read_lock/unlock(). I don't >> think it's good to wrap swap_read_page() with it. After all, some >> complex operations are done in swap_read_page(), including >> blk_io_schedule(). >> > > In that case then have the patches to make get/put_swap_device to use > percpu_ref first. And the patch to to fix the race in do_swap_page > later in another patch. > > Patch 2 is mixing the two. > Looks like a good way to organize this patch series. Many thanks! > Tim > . >
