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Message-ID: <20160906113542.08690455@gandalf.local.home>
Date: Tue, 6 Sep 2016 11:35:42 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Hui Zhu <zhuhui@...omi.com>
Cc: <minchan@...nel.org>, <ngupta@...are.org>,
<sergey.senozhatsky.work@...il.com>, <hughd@...gle.com>,
<mingo@...hat.com>, <peterz@...radead.org>, <acme@...nel.org>,
<alexander.shishkin@...ux.intel.com>, <akpm@...ux-foundation.org>,
<mhocko@...e.com>, <hannes@...xchg.org>,
<mgorman@...hsingularity.net>, <vbabka@...e.cz>,
<redkoi@...tuozzo.com>, <luto@...nel.org>,
<kirill.shutemov@...ux.intel.com>, <geliangtang@....com>,
<baiyaowei@...s.chinamobile.com>, <dan.j.williams@...el.com>,
<vdavydov@...tuozzo.com>, <aarcange@...hat.com>,
<dvlasenk@...hat.com>, <jmarchan@...hat.com>, <koct9i@...il.com>,
<yang.shi@...aro.org>, <dave.hansen@...ux.intel.com>,
<vkuznets@...hat.com>, <vitalywool@...il.com>,
<ross.zwisler@...ux.intel.com>, <tglx@...utronix.de>,
<kwapulinski.piotr@...il.com>, <axboe@...com>,
<mchristi@...hat.com>, <joe@...ches.com>, <namit@...are.com>,
<riel@...hat.com>, <linux-kernel@...r.kernel.org>,
<linux-mm@...ck.org>, <teawater@...il.com>
Subject: Re: [RFC 2/4] Add non-swap page flag to mark a page will not swap
On Mon, 22 Aug 2016 16:25:07 +0800
Hui Zhu <zhuhui@...omi.com> wrote:
>
> --- a/include/linux/mm_inline.h
> +++ b/include/linux/mm_inline.h
> @@ -46,15 +46,31 @@ static __always_inline void update_lru_size(struct lruvec *lruvec,
> static __always_inline void add_page_to_lru_list(struct page *page,
> struct lruvec *lruvec, enum lru_list lru)
> {
> - update_lru_size(lruvec, lru, page_zonenum(page), hpage_nr_pages(page));
> + int nr_pages = hpage_nr_pages(page);
> + enum zone_type zid = page_zonenum(page);
> +#ifdef CONFIG_NON_SWAP
> + if (PageNonSwap(page)) {
Can't we just have PageNonSwap() return false when CONFIG_NON_SWAP is
not defined, and lose the ugly #ifdef? It will make this much cleaner.
> + lru = LRU_UNEVICTABLE;
> + update_lru_size(lruvec, NR_NON_SWAP, zid, nr_pages);
> + }
> +#endif
> + update_lru_size(lruvec, lru, zid, nr_pages);
> list_add(&page->lru, &lruvec->lists[lru]);
> }
>
> static __always_inline void del_page_from_lru_list(struct page *page,
> struct lruvec *lruvec, enum lru_list lru)
> {
> + int nr_pages = hpage_nr_pages(page);
> + enum zone_type zid = page_zonenum(page);
> +#ifdef CONFIG_NON_SWAP
> + if (PageNonSwap(page)) {
> + lru = LRU_UNEVICTABLE;
> + update_lru_size(lruvec, NR_NON_SWAP, zid, -nr_pages);
> + }
> +#endif
> list_del(&page->lru);
> - update_lru_size(lruvec, lru, page_zonenum(page), -hpage_nr_pages(page));
> + update_lru_size(lruvec, lru, zid, -nr_pages);
> }
>
> /**
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index d572b78..da08d20 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -138,6 +138,9 @@ enum zone_stat_item {
> NUMA_OTHER, /* allocation from other node */
> #endif
> NR_FREE_CMA_PAGES,
> +#ifdef CONFIG_NON_SWAP
> + NR_NON_SWAP,
> +#endif
Is it bad to have NR_NON_SWAP defined as an enum if CONFIG_NON_SWAP is
not defined?
> NR_VM_ZONE_STAT_ITEMS };
>
> enum node_stat_item {
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 74e4dda..0cd80db9 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -105,6 +105,9 @@ enum pageflags {
> PG_young,
> PG_idle,
> #endif
> +#ifdef CONFIG_NON_SWAP
> + PG_non_swap,
> +#endif
Here too.
> __NR_PAGEFLAGS,
>
> /* Filesystems */
> @@ -303,6 +306,11 @@ PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
> PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
> TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
>
> +#ifdef CONFIG_NON_SWAP
> +PAGEFLAG(NonSwap, non_swap, PF_NO_TAIL)
> + TESTSCFLAG(NonSwap, non_swap, PF_NO_TAIL)
> +#endif
> +
> #ifdef CONFIG_HIGHMEM
> /*
> * Must use a macro here due to header dependency issues. page_zone() is not
> diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
> index 5a81ab4..1c0ccc9 100644
> --- a/include/trace/events/mmflags.h
> +++ b/include/trace/events/mmflags.h
> @@ -79,6 +79,12 @@
> #define IF_HAVE_PG_IDLE(flag,string)
> #endif
>
> +#ifdef CONFIG_NON_SWAP
> +#define IF_HAVE_PG_NON_SWAP(flag,string) ,{1UL << flag, string}
> +#else
> +#define IF_HAVE_PG_NON_SWAP(flag,string)
> +#endif
> +
> #define __def_pageflag_names \
> {1UL << PG_locked, "locked" }, \
> {1UL << PG_error, "error" }, \
> @@ -104,7 +110,8 @@ IF_HAVE_PG_MLOCK(PG_mlocked, "mlocked" ) \
> IF_HAVE_PG_UNCACHED(PG_uncached, "uncached" ) \
> IF_HAVE_PG_HWPOISON(PG_hwpoison, "hwpoison" ) \
> IF_HAVE_PG_IDLE(PG_young, "young" ) \
> -IF_HAVE_PG_IDLE(PG_idle, "idle" )
> +IF_HAVE_PG_IDLE(PG_idle, "idle" ) \
> +IF_HAVE_PG_NON_SWAP(PG_non_swap, "non_swap" )
>
> #define show_page_flags(flags) \
> (flags) ? __print_flags(flags, "|", \
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index b7a525a..a7e4153 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -160,6 +160,10 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
> const unsigned long mmun_start = addr;
> const unsigned long mmun_end = addr + PAGE_SIZE;
> struct mem_cgroup *memcg;
> + pte_t pte;
> +#ifdef CONFIG_NON_SWAP
> + bool non_swap;
> +#endif
>
> err = mem_cgroup_try_charge(kpage, vma->vm_mm, GFP_KERNEL, &memcg,
> false);
> @@ -176,6 +180,11 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
> goto unlock;
>
> get_page(kpage);
> +#ifdef CONFIG_NON_SWAP
> + non_swap = TestClearPageNonSwap(page);
Can't we have TestClearPageNonSwap() return false when CONFIG_NON_SWAP
is not defined, and lose the ugly #ifdefs here in the code?
> + if (non_swap)
> + SetPageNonSwap(kpage);
Make SetPageNonSwap() a nop (or warning) if CONFIG_NON_SWAP is not
defined.
> +#endif
> page_add_new_anon_rmap(kpage, vma, addr, false);
> mem_cgroup_commit_charge(kpage, memcg, false, false);
> lru_cache_add_active_or_unevictable(kpage, vma);
> @@ -187,7 +196,12 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
>
> flush_cache_page(vma, addr, pte_pfn(*ptep));
> ptep_clear_flush_notify(vma, addr, ptep);
> - set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
> + pte = mk_pte(kpage, vma->vm_page_prot);
> +#ifdef CONFIG_NON_SWAP
> + if (non_swap)
> + pte = pte_wrprotect(pte);
> +#endif
Again, I hate the added #ifdef in code, when we can have stub functions
make non_swap false.
A lot of the #ifdef's can be nuked with proper stub functions, which
makes maintaining and reviewing the code much easier.
-- Steve
> + set_pte_at_notify(mm, addr, ptep, pte);
>
> page_remove_rmap(page, false);
> if (!page_mapped(page))
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 57ecdb3..d8d4b41 100644
> --- a/mm/Kconfig
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