Messages in this thread | | | Subject | Re: [External] Re: [PATCH] mm/memory.c: Introduce non-atomic __{Set,Clear}PageSwapCache | From | "Xu, Yanfei" <> | Date | Wed, 21 Oct 2020 10:52:12 +0800 |
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On 10/20/20 9:08 PM, Muchun Song wrote: > On Tue, Oct 20, 2020 at 7:51 PM Xu, Yanfei <yanfei.xu@windriver.com> wrote: >> >> >> >> On 10/19/20 10:58 PM, Muchun Song wrote: >>> On Mon, Oct 19, 2020 at 8:31 PM Michal Hocko <mhocko@suse.com> wrote: >>>> >>>> On Mon 19-10-20 18:15:20, Muchun Song wrote: >>>>> For the exclusive reference page, the non-atomic operations is enough, >>>>> so replace them to non-atomic operations. >>>> >>>> I do expect you do not see any difference in runtime and this is mostly >>>> driven by the code reading, right? Being explicit about this in the code >>>> would be preferred. >>> >>> Yeah, just code reading.And the set_bit and __set_bit is actually different >>> on some architectures. Thanks. >>> >>>> >>>> No objection to the change. >>>> >>>>> Signed-off-by: Muchun Song <songmuchun@bytedance.com> >>>> >>>> With an improved changelog >>>> Acked-by: Michal Hocko <mhocko@suse.com> >>>> >>>>> --- >>>>> include/linux/page-flags.h | 2 ++ >>>>> mm/memory.c | 4 ++-- >>>>> 2 files changed, 4 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h >>>>> index fbbb841a9346..ec039dde5e4b 100644 >>>>> --- a/include/linux/page-flags.h >>>>> +++ b/include/linux/page-flags.h >>>>> @@ -401,6 +401,8 @@ static __always_inline int PageSwapCache(struct page *page) >>>>> } >>>>> SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) >>>>> CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) >>>>> +__SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) >>>>> +__CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) >>>>> #else >>>>> PAGEFLAG_FALSE(SwapCache) >>>>> #endif >>>>> diff --git a/mm/memory.c b/mm/memory.c >>>>> index 2d267ef6621a..02dd62da26e0 100644 >>>>> --- a/mm/memory.c >>>>> +++ b/mm/memory.c >>>>> @@ -3128,10 +3128,10 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) >>>>> set_page_private(page, entry.val); >>>>> >>>>> /* Tell memcg to use swap ownership records */ >>>>> - SetPageSwapCache(page); >>>>> + __SetPageSwapCache(page); >> >> Good evening, Muchun. I found there are still some places could be >> replaced with __SetPageSwapCache(). Such as shmem_replace_page(), why > > Yeah, thanks for your suggestion. > >> PG_locked has been set before SetPageSwapCache() is involved. > > In this case, It doesn't matter whether PG_locked is set before > SetPageSwapCache. > Sorry for this mistake. PG_locked is used for disk I/O. >> >> Would you please to check the rest places? :) > > Ok, I'll take a look. Thanks. > >> >> Thanks >> >> Acked-by: Yanfei Xu <yanfei.xu@windriver.com> >> >>>>> err = mem_cgroup_charge(page, vma->vm_mm, >>>>> GFP_KERNEL); >>>>> - ClearPageSwapCache(page); >>>>> + __ClearPageSwapCache(page); >>>>> if (err) { >>>>> ret = VM_FAULT_OOM; >>>>> goto out_page; >>>>> -- >>>>> 2.20.1 >>>>> >>>> >>>> -- >>>> Michal Hocko >>>> SUSE Labs >>> >>> >>> > > > > -- > Yours, > Muchun >
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