Messages in this thread | | | Subject | Re: [External] Re: [PATCH] mm/memory.c: Introduce non-atomic __{Set,Clear}PageSwapCache | From | "Xu, Yanfei" <> | Date | Tue, 20 Oct 2020 19:50:32 +0800 |
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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 PG_locked has been set before SetPageSwapCache() is involved.
Would you please to check the rest places? :)
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 > > >
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