Messages in this thread | | | From | "Du, Fan" <> | Subject | RE: [PATCH v4] Add /proc/PID/smaps support for DAX | Date | Fri, 27 Oct 2017 02:49:45 +0000 |
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>-----Original Message----- >From: linux-kernel-owner@vger.kernel.org >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Dan Williams >Sent: Thursday, October 26, 2017 5:17 PM >To: Du, Fan <fan.du@intel.com> >Cc: Andrew Morton <akpm@linux-foundation.org>; Christoph Hellwig ><hch@lst.de>; Hansen, Dave <dave.hansen@intel.com>; Michal Hocko ><mhocko@kernel.org>; linux-kernel@vger.kernel.org >Subject: Re: [PATCH v4] Add /proc/PID/smaps support for DAX > >On Wed, Oct 25, 2017 at 10:13 PM, Fan Du <fan.du@intel.com> wrote: >> >> Memory behind device DAX is not attached into normal memory >> management system, when user mmap /dev/dax, smaps part is >> currently missing, so no idea for user to check how much >> device DAX memory are actually used in practice. >> >> Whether vma is backed up by normal page,huge page, or both >> at the same time, this makes no difference for device DAX >> user so far. >> >> Using existing smaps structure is enough to do the job, so >> this patch tries to use existing RSS/PSS stuff for statistics. >> An example reading is like this: >> ---------------------------------------------------- >> 7f30fe200000-7f3102200000 rw-s 00000000 00:06 19567 >/dev/dax12.0 >> Size: 65536 kB >> KernelPageSize: 4 kB >> MMUPageSize: 4 kB >> Rss: 65536 kB >> Pss: 65536 kB >> Shared_Clean: 0 kB >> Shared_Dirty: 0 kB >> Private_Clean: 0 kB >> Private_Dirty: 65536 kB >> Referenced: 65536 kB >> Anonymous: 0 kB >> LazyFree: 0 kB >> AnonHugePages: 0 kB >> ShmemPmdMapped: 0 kB >> Shared_Hugetlb: 0 kB >> Private_Hugetlb: 0 kB >> Swap: 0 kB >> SwapPss: 0 kB >> Locked: 65536 kB >> ProtectionKey: 0 >> VmFlags: rd wr sh mr mw me ms mm hg >> >> Signed-off-by: Fan Du <fan.du@intel.com> >> --- >> v4: >> * Merge device DAX readings into existing smap counters >> for simplicity. >> >> v3: >> * Elaborate more about the usage suggested by Michal Hocko >> >> v2: >> * Using pte_devmap to check valid pfn page structure, >> Pointed out by Dan. thx! >> fs/proc/task_mmu.c | 74 >++++++++++++++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 72 insertions(+), 2 deletions(-) >> >> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c >> index 5589b4b..9b2d3e6 100644 >> --- a/fs/proc/task_mmu.c >> +++ b/fs/proc/task_mmu.c >> @@ -507,6 +507,55 @@ static void smaps_account(struct mem_size_stats >*mss, struct page *page, >> } >> } >> >> +/* page structure behind DAX mappings is NOT compound page >> + * when it's a huge page mappings, so introduce new API to >> + * account for both PMD and PUD mapping. >> + */ >> +static void smaps_account_dax_huge(struct mem_size_stats *mss, >> + struct page *page, unsigned long size, bool >young, bool dirty) >> +{ >> + int mapcount = page_mapcount(page); >> + >> + if (PageAnon(page)) { >> + mss->anonymous += size; >> + if (!PageSwapBacked(page) && !dirty >&& !PageDirty(page)) >> + mss->lazyfree += size; >> + } >> + >> + mss->resident += size; >> + /* Accumulate the size in pages that have been accessed. */ >> + if (young || page_is_young(page) || PageReferenced(page)) >> + mss->referenced += size; >> + >> + /* >> + * page_count(page) == 1 guarantees the page is mapped exactly >once. >> + * If any subpage of the compound page mapped with PTE it >would elevate >> + * page_count(). >> + */ >> + if (page_count(page) == 1) { >> + if (dirty || PageDirty(page)) >> + mss->private_dirty += size; >> + else >> + mss->private_clean += size; >> + mss->pss += (u64)size << PSS_SHIFT; >> + return; >> + } >> + >> + if (mapcount >= 2) { >> + if (dirty || PageDirty(page)) >> + mss->shared_dirty += size; >> + else >> + mss->shared_clean += size; >> + mss->pss += (size << PSS_SHIFT) / mapcount; >> + } else { >> + if (dirty || PageDirty(page)) >> + mss->private_dirty += size; >> + else >> + mss->private_clean += size; >> + mss->pss += size << PSS_SHIFT; >> + } >> +} >> + >> #ifdef CONFIG_SHMEM >> static int smaps_pte_hole(unsigned long addr, unsigned long end, >> struct mm_walk *walk) >> @@ -528,7 +577,16 @@ static void smaps_pte_entry(pte_t *pte, unsigned >long addr, >> struct page *page = NULL; >> >> if (pte_present(*pte)) { >> - page = vm_normal_page(vma, addr, *pte); >> + if (!vma_is_dax(vma)) >> + page = vm_normal_page(vma, addr, *pte); >> + else if (pte_devmap(*pte)) { >> + struct dev_pagemap *pgmap; >> + >> + pgmap = get_dev_pagemap(pte_pfn(*pte), >NULL); > >Where do you do the put_dev_pagemap?
Oops, my bad :( will fix this in next version.
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