From: akpm@linux-foundation.org
To: arnd@arndb.de, bp@alien8.de, catalin.marinas@arm.com,
cl@linux.com, dan.j.williams@intel.com,
dave.hansen@linux.intel.com, elena.reshetova@intel.com,
guro@fb.com, hagen@jauu.net, hpa@zytor.com, jejb@linux.ibm.com,
kirill@shutemov.name, luto@kernel.org, mark.rutland@arm.com,
mingo@redhat.com, mm-commits@vger.kernel.org,
mtk.manpages@gmail.com, oliver.sang@intel.com,
palmer@dabbelt.com, palmerdabbelt@google.com,
paul.walmsley@sifive.com, peterz@infradead.org,
rick.p.edgecombe@intel.com, rppt@linux.ibm.com,
shakeelb@google.com, shuah@kernel.org, tglx@linutronix.de,
tycho@tycho.ws, viro@zeniv.linux.org.uk, will@kernel.org,
willy@infradead.org
Subject: + mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3.patch added to -mm tree
Date: Tue, 20 Apr 2021 17:25:27 -0700 [thread overview]
Message-ID: <20210421002527.FqlcjoMYq%akpm@linux-foundation.org> (raw)
The patch titled
Subject: secretmem: optimize page_is_secretmem()
has been added to the -mm tree. Its filename is
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mike Rapoport <rppt@linux.ibm.com>
Subject: secretmem: optimize page_is_secretmem()
Kernel test robot reported -4.2% regression of
will-it-scale.per_thread_ops due to commit "mm: introduce memfd_secret
system call to create "secret" memory areas".
The perf profile of the test indicated that the regression is caused by
page_is_secretmem() called from gup_pte_range() (inlined by
gup_pgd_range):
27.76 +2.5 30.23 perf-profile.children.cycles-pp.gup_pgd_range
0.00 +3.2 3.19 ± 2% perf-profile.children.cycles-pp.page_mapping
0.00 +3.7 3.66 ± 2% perf-profile.children.cycles-pp.page_is_secretmem
Further analysis showed that the slow down happens because neither
page_is_secretmem() nor page_mapping() are not inline and moreover,
multiple page flags checks in page_mapping() involve calling
compound_head() several times for the same page.
Make page_is_secretmem() inline and replace page_mapping() with page flag
checks that do not imply page-to-head conversion.
Link: https://lkml.kernel.org/r/20210420150049.14031-3-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/secretmem.h | 26 +++++++++++++++++++++++++-
mm/secretmem.c | 12 +-----------
2 files changed, 26 insertions(+), 12 deletions(-)
--- a/include/linux/secretmem.h~mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3
+++ a/include/linux/secretmem.h
@@ -4,8 +4,32 @@
#ifdef CONFIG_SECRETMEM
+extern const struct address_space_operations secretmem_aops;
+
+static inline bool page_is_secretmem(struct page *page)
+{
+ struct address_space *mapping;
+
+ /*
+ * Using page_mapping() is quite slow because of the actual call
+ * instruction and repeated compound_head(page) inside the
+ * page_mapping() function.
+ * We know that secretmem pages are not compound and LRU so we can
+ * save a couple of cycles here.
+ */
+ if (PageCompound(page) || !PageLRU(page))
+ return false;
+
+ mapping = (struct address_space *)
+ ((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
+
+ if (mapping != page->mapping)
+ return false;
+
+ return page->mapping->a_ops == &secretmem_aops;
+}
+
bool vma_is_secretmem(struct vm_area_struct *vma);
-bool page_is_secretmem(struct page *page);
#else
--- a/mm/secretmem.c~mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3
+++ a/mm/secretmem.c
@@ -137,22 +137,12 @@ static void secretmem_freepage(struct pa
clear_highpage(page);
}
-static const struct address_space_operations secretmem_aops = {
+const struct address_space_operations secretmem_aops = {
.freepage = secretmem_freepage,
.migratepage = secretmem_migratepage,
.isolate_page = secretmem_isolate_page,
};
-bool page_is_secretmem(struct page *page)
-{
- struct address_space *mapping = page_mapping(page);
-
- if (!mapping)
- return false;
-
- return mapping->a_ops == &secretmem_aops;
-}
-
static struct vfsmount *secretmem_mnt;
static struct file *secretmem_file_create(unsigned long flags)
_
Patches currently in -mm which might be from rppt@linux.ibm.com are
mm-cma-rename-pf_memalloc_nocma-to-pf_memalloc_pin-fix.patch
mmap-make-mlock_future_check-global.patch
riscv-kconfig-make-direct-map-manipulation-options-depend-on-mmu.patch
set_memory-allow-set_direct_map__noflush-for-multiple-pages.patch
set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-3.patch
pm-hibernate-disable-when-there-are-active-secretmem-users.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant-fix.patch
secretmem-test-add-basic-selftest-for-memfd_secret2.patch
secretmem-test-add-basic-selftest-for-memfd_secret2-fix.patch
reply other threads:[~2021-04-21 0:25 UTC|newest]
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