From: Peter Xu <peterx@redhat.com>
To: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>,
David Hildenbrand <david@redhat.com>,
David Rientjes <rientjes@google.com>,
Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@suse.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
SeongJae Park <sj@kernel.org>, Song Liu <songliubraving@fb.com>,
Vlastimil Babka <vbabka@suse.cz>, Yang Shi <shy828301@gmail.com>,
Zi Yan <ziy@nvidia.com>,
linux-mm@kvack.org, Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Axel Rasmussen <axelrasmussen@google.com>,
Chris Kennelly <ckennelly@google.com>,
Chris Zankel <chris@zankel.net>, Helge Deller <deller@gmx.de>,
Hugh Dickins <hughd@google.com>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
Jens Axboe <axboe@kernel.dk>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matt Turner <mattst88@gmail.com>,
Max Filippov <jcmvbkbc@gmail.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Minchan Kim <minchan@kernel.org>,
Patrick Xia <patrickx@google.com>,
Pavel Begunkov <asml.silence@gmail.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v3 01/12] mm/khugepaged: record SCAN_PMD_MAPPED when scan_pmd() finds THP
Date: Tue, 26 Apr 2022 20:26:32 -0400 [thread overview]
Message-ID: <YmiNuO2U96yhMeyv@xz-m1.local> (raw)
In-Reply-To: <20220426144412.742113-2-zokeefe@google.com>
Hi, Zach,
On Tue, Apr 26, 2022 at 07:44:01AM -0700, Zach O'Keefe wrote:
> When scanning an anon pmd to see if it's eligible for collapse, return
> SCAN_PMD_MAPPED if the pmd already maps a THP. Note that
> SCAN_PMD_MAPPED is different from SCAN_PAGE_COMPOUND used in the
> file-collapse path, since the latter might identify pte-mapped compound
> pages. This is required by MADV_COLLAPSE which necessarily needs to
> know what hugepage-aligned/sized regions are already pmd-mapped.
>
> Signed-off-by: Zach O'Keefe <zokeefe@google.com>
> Reported-by: kernel test robot <lkp@intel.com>
IIUC we don't need to attach this reported-by if this is not a bugfix. I
think you can simply fix all issues reported by the test bot and only
attach the line if the patch is fixing the problem that the bot was
reporting explicitly.
> ---
> include/trace/events/huge_memory.h | 3 ++-
> mm/internal.h | 1 +
> mm/khugepaged.c | 30 ++++++++++++++++++++++++++----
> mm/rmap.c | 15 +++++++++++++--
> 4 files changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
> index d651f3437367..9faa678e0a5b 100644
> --- a/include/trace/events/huge_memory.h
> +++ b/include/trace/events/huge_memory.h
> @@ -33,7 +33,8 @@
> EM( SCAN_ALLOC_HUGE_PAGE_FAIL, "alloc_huge_page_failed") \
> EM( SCAN_CGROUP_CHARGE_FAIL, "ccgroup_charge_failed") \
> EM( SCAN_TRUNCATED, "truncated") \
> - EMe(SCAN_PAGE_HAS_PRIVATE, "page_has_private") \
> + EM( SCAN_PAGE_HAS_PRIVATE, "page_has_private") \
> + EMe(SCAN_PMD_MAPPED, "page_pmd_mapped") \
Nit: IMHO it can be put even in the middle so we don't need to touch the
EMe() every time. :)
Apart from that, it does sound proper to me to put SCAN_PMD_MAPPED to be
right after SCAN_PMD_NULL anyway.
>
> #undef EM
> #undef EMe
> diff --git a/mm/internal.h b/mm/internal.h
> index 0667abd57634..51ae9f71a2a3 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -172,6 +172,7 @@ extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason
> /*
> * in mm/rmap.c:
> */
> +pmd_t *mm_find_pmd_raw(struct mm_struct *mm, unsigned long address);
> extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address);
>
> /*
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index ba8dbd1825da..2933b13fc975 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -51,6 +51,7 @@ enum scan_result {
> SCAN_CGROUP_CHARGE_FAIL,
> SCAN_TRUNCATED,
> SCAN_PAGE_HAS_PRIVATE,
> + SCAN_PMD_MAPPED,
> };
>
> #define CREATE_TRACE_POINTS
> @@ -987,6 +988,29 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
> return 0;
> }
>
> +static int find_pmd_or_thp_or_none(struct mm_struct *mm,
> + unsigned long address,
> + pmd_t **pmd)
> +{
> + pmd_t pmde;
> +
> + *pmd = mm_find_pmd_raw(mm, address);
> + if (!*pmd)
> + return SCAN_PMD_NULL;
> +
> + pmde = pmd_read_atomic(*pmd);
> +
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> + /* See comments in pmd_none_or_trans_huge_or_clear_bad() */
> + barrier();
> +#endif
> + if (!pmd_present(pmde) || pmd_none(pmde))
Could we drop the pmd_none() check? I assume !pmd_present() should have
covered that case already?
> + return SCAN_PMD_NULL;
> + if (pmd_trans_huge(pmde))
> + return SCAN_PMD_MAPPED;
> + return SCAN_SUCCEED;
> +}
> +
> /*
> * Bring missing pages in from swap, to complete THP collapse.
> * Only done if khugepaged_scan_pmd believes it is worthwhile.
> @@ -1238,11 +1262,9 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
>
> VM_BUG_ON(address & ~HPAGE_PMD_MASK);
>
> - pmd = mm_find_pmd(mm, address);
> - if (!pmd) {
> - result = SCAN_PMD_NULL;
> + result = find_pmd_or_thp_or_none(mm, address, &pmd);
> + if (result != SCAN_SUCCEED)
> goto out;
> - }
>
> memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
> pte = pte_offset_map_lock(mm, pmd, address, &ptl);
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 61e63db5dc6f..49817f35e65c 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -759,13 +759,12 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
> return vma_address(page, vma);
> }
>
> -pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
> +pmd_t *mm_find_pmd_raw(struct mm_struct *mm, unsigned long address)
> {
> pgd_t *pgd;
> p4d_t *p4d;
> pud_t *pud;
> pmd_t *pmd = NULL;
> - pmd_t pmde;
>
> pgd = pgd_offset(mm, address);
> if (!pgd_present(*pgd))
> @@ -780,6 +779,18 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
> goto out;
>
> pmd = pmd_offset(pud, address);
> +out:
> + return pmd;
> +}
> +
> +pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
> +{
> + pmd_t pmde;
> + pmd_t *pmd;
> +
> + pmd = mm_find_pmd_raw(mm, address);
> + if (!pmd)
> + goto out;
> /*
> * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
> * without holding anon_vma lock for write. So when looking for a
> --
> 2.36.0.rc2.479.g8af0fa9b8e-goog
>
--
Peter Xu
next prev parent reply other threads:[~2022-04-27 0:26 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 14:44 [PATCH v3 00/12] mm: userspace hugepage collapse Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 01/12] mm/khugepaged: record SCAN_PMD_MAPPED when scan_pmd() finds THP Zach O'Keefe
2022-04-27 0:26 ` Peter Xu [this message]
2022-04-27 15:48 ` Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 02/12] mm/khugepaged: add struct collapse_control Zach O'Keefe
2022-04-27 19:49 ` Peter Xu
2022-04-28 0:19 ` Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 03/12] mm/khugepaged: make hugepage allocation context-specific Zach O'Keefe
2022-04-27 20:04 ` Peter Xu
2022-04-28 0:51 ` Zach O'Keefe
2022-04-28 14:51 ` Peter Xu
2022-04-28 15:37 ` Zach O'Keefe
2022-04-28 15:52 ` Peter Xu
2022-04-26 14:44 ` [PATCH v3 04/12] mm/khugepaged: add struct collapse_result Zach O'Keefe
2022-04-27 20:47 ` Peter Xu
2022-04-28 21:59 ` Zach O'Keefe
2022-04-28 23:21 ` Peter Xu
2022-04-29 16:01 ` Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 05/12] mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 06/12] mm/khugepaged: remove khugepaged prefix from shared collapse functions Zach O'Keefe
2022-04-27 21:10 ` Peter Xu
2022-04-28 22:51 ` Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 07/12] mm/khugepaged: add flag to ignore khugepaged_max_ptes_* Zach O'Keefe
2022-04-27 21:12 ` Peter Xu
2022-04-29 14:26 ` Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 08/12] mm/khugepaged: add flag to ignore page young/referenced requirement Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 09/12] mm/madvise: add MADV_COLLAPSE to process_madvise() Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 10/12] selftests/vm: modularize collapse selftests Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 11/12] selftests/vm: add MADV_COLLAPSE collapse context to selftests Zach O'Keefe
2022-04-26 14:44 ` [PATCH v3 12/12] selftests/vm: add test to verify recollapse of THPs Zach O'Keefe
2022-04-26 20:23 ` [PATCH v3 00/12] mm: userspace hugepage collapse Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YmiNuO2U96yhMeyv@xz-m1.local \
--to=peterx@redhat.com \
--cc=James.Bottomley@HansenPartnership.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=alex.shi@linux.alibaba.com \
--cc=arnd@arndb.de \
--cc=asml.silence@gmail.com \
--cc=axboe@kernel.dk \
--cc=axelrasmussen@google.com \
--cc=chris@zankel.net \
--cc=ckennelly@google.com \
--cc=david@redhat.com \
--cc=deller@gmx.de \
--cc=hughd@google.com \
--cc=ink@jurassic.park.msu.ru \
--cc=jcmvbkbc@gmail.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linmiaohe@huawei.com \
--cc=linux-mm@kvack.org \
--cc=lkp@intel.com \
--cc=mattst88@gmail.com \
--cc=mhocko@suse.com \
--cc=minchan@kernel.org \
--cc=pasha.tatashin@soleen.com \
--cc=patrickx@google.com \
--cc=rientjes@google.com \
--cc=shy828301@gmail.com \
--cc=sj@kernel.org \
--cc=songliubraving@fb.com \
--cc=tsbogend@alpha.franken.de \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
--cc=ziy@nvidia.com \
--cc=zokeefe@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).