* + thp-allocate-memory-in-khugepaged-outside-of-mmap_sem-write-mode.patch added to -mm tree
@ 2010-12-15 23:57 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2010-12-15 23:57 UTC (permalink / raw)
To: mm-commits; +Cc: aarcange
The patch titled
thp: allocate memory in khugepaged outside of mmap_sem write mode
has been added to the -mm tree. Its filename is
thp-allocate-memory-in-khugepaged-outside-of-mmap_sem-write-mode.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: thp: allocate memory in khugepaged outside of mmap_sem write mode
From: Andrea Arcangeli <aarcange@redhat.com>
This tries to be more friendly to filesystem in userland, with userland
backends that allocate memory in the I/O paths and that could deadlock if
khugepaged holds the mmap_sem write mode of the userland backend while
allocating memory. Memory allocation may wait for writeback I/O
completion from the daemon that may be blocked in the mmap_sem read mode
if a page fault happens and the daemon wasn't using mlock for the memory
required for the I/O submission and completion.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/huge_memory.c | 50 +++++++++++++++++++++++++++------------------
1 file changed, 31 insertions(+), 19 deletions(-)
diff -puN mm/huge_memory.c~thp-allocate-memory-in-khugepaged-outside-of-mmap_sem-write-mode mm/huge_memory.c
--- a/mm/huge_memory.c~thp-allocate-memory-in-khugepaged-outside-of-mmap_sem-write-mode
+++ a/mm/huge_memory.c
@@ -1680,9 +1680,34 @@ static void collapse_huge_page(struct mm
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
#ifndef CONFIG_NUMA
VM_BUG_ON(!*hpage);
+ new_page = *hpage;
#else
VM_BUG_ON(*hpage);
+ /*
+ * Allocate the page while the vma is still valid and under
+ * the mmap_sem read mode so there is no memory allocation
+ * later when we take the mmap_sem in write mode. This is more
+ * friendly behavior (OTOH it may actually hide bugs) to
+ * filesystems in userland with daemons allocating memory in
+ * the userland I/O paths. Allocating memory with the
+ * mmap_sem in read mode is good idea also to allow greater
+ * scalability.
+ */
+ new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address);
+ if (unlikely(!new_page)) {
+ up_read(&mm->mmap_sem);
+ *hpage = ERR_PTR(-ENOMEM);
+ return;
+ }
#endif
+ if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
+ up_read(&mm->mmap_sem);
+ put_page(new_page);
+ return;
+ }
+
+ /* after allocating the hugepage upgrade to mmap_sem write mode */
+ up_read(&mm->mmap_sem);
/*
* Prevent all access to pagetables with the exception of
@@ -1720,18 +1745,6 @@ static void collapse_huge_page(struct mm
if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
goto out;
-#ifndef CONFIG_NUMA
- new_page = *hpage;
-#else
- new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address);
- if (unlikely(!new_page)) {
- *hpage = ERR_PTR(-ENOMEM);
- goto out;
- }
-#endif
- if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
- goto out_put_page;
-
anon_vma_lock(vma->anon_vma);
pte = pte_offset_map(pmd, address);
@@ -1759,7 +1772,7 @@ static void collapse_huge_page(struct mm
spin_unlock(&mm->page_table_lock);
anon_vma_unlock(vma->anon_vma);
mem_cgroup_uncharge_page(new_page);
- goto out_put_page;
+ goto out;
}
/*
@@ -1798,15 +1811,15 @@ static void collapse_huge_page(struct mm
*hpage = NULL;
#endif
khugepaged_pages_collapsed++;
-out:
+out_up_write:
up_write(&mm->mmap_sem);
return;
-out_put_page:
+out:
#ifdef CONFIG_NUMA
put_page(new_page);
#endif
- goto out;
+ goto out_up_write;
}
static int khugepaged_scan_pmd(struct mm_struct *mm,
@@ -1865,10 +1878,9 @@ static int khugepaged_scan_pmd(struct mm
ret = 1;
out_unmap:
pte_unmap_unlock(pte, ptl);
- if (ret) {
- up_read(&mm->mmap_sem);
+ if (ret)
+ /* collapse_huge_page will return with the mmap_sem released */
collapse_huge_page(mm, address, hpage);
- }
out:
return ret;
}
_
Patches currently in -mm which might be from aarcange@redhat.com are
mm-compaction-add-trace-events-for-memory-compaction-activity.patch
mm-vmscan-convert-lumpy_mode-into-a-bitmask.patch
mm-vmscan-reclaim-order-0-and-use-compaction-instead-of-lumpy-reclaim.patch
mm-vmscan-reclaim-order-0-and-use-compaction-instead-of-lumpy-reclaim-fix.patch
mm-migration-allow-migration-to-operate-asynchronously-and-avoid-synchronous-compaction-in-the-faster-path.patch
mm-migration-allow-migration-to-operate-asynchronously-and-avoid-synchronous-compaction-in-the-faster-path-fix.patch
mm-migration-cleanup-migrate_pages-api-by-matching-types-for-offlining-and-sync.patch
mm-compaction-perform-a-faster-migration-scan-when-migrating-asynchronously.patch
mm-vmscan-rename-lumpy_mode-to-reclaim_mode.patch
mm-vmscan-rename-lumpy_mode-to-reclaim_mode-fix.patch
thp-ksm-free-swap-when-swapcache-page-is-replaced.patch
thp-fix-bad_page-to-show-the-real-reason-the-page-is-bad.patch
thp-transparent-hugepage-support-documentation.patch
thp-mm-define-madv_hugepage.patch
thp-compound_lock.patch
thp-alter-compound-get_page-put_page.patch
thp-put_page-recheck-pagehead-after-releasing-the-compound_lock.patch
thp-update-futex-compound-knowledge.patch
thp-clear-compound-mapping.patch
thp-add-native_set_pmd_at.patch
thp-add-pmd-paravirt-ops.patch
thp-no-paravirt-version-of-pmd-ops.patch
thp-export-maybe_mkwrite.patch
thp-comment-reminder-in-destroy_compound_page.patch
thp-config_transparent_hugepage.patch
thp-special-pmd_trans_-functions.patch
thp-add-pmd-mangling-generic-functions.patch
thp-add-pmd-mangling-functions-to-x86.patch
thp-bail-out-gup_fast-on-splitting-pmd.patch
thp-pte-alloc-trans-splitting.patch
thp-add-pmd-mmu_notifier-helpers.patch
thp-clear-page-compound.patch
thp-add-pmd_huge_pte-to-mm_struct.patch
thp-split_huge_page_mm-vma.patch
thp-split_huge_page-paging.patch
thp-clear_copy_huge_page.patch
thp-_gfp_no_kswapd.patch
thp-dont-alloc-harder-for-gfp-nomemalloc-even-if-nowait.patch
thp-transparent-hugepage-core.patch
thp-split_huge_page-anon_vma-ordering-dependency.patch
thp-verify-pmd_trans_huge-isnt-leaking.patch
thp-madvisemadv_hugepage.patch
thp-add-pagetranscompound.patch
thp-pmd_trans_huge-migrate-bugcheck.patch
thp-memcg-compound.patch
thp-transhuge-memcg-commit-tail-pages-at-charge.patch
thp-memcg-huge-memory.patch
thp-transparent-hugepage-vmstat.patch
thp-khugepaged.patch
thp-khugepaged-vma-merge.patch
thp-skip-transhuge-pages-in-ksm-for-now.patch
thp-remove-pg_buddy.patch
thp-add-x86-32bit-support.patch
thp-mincore-transparent-hugepage-support.patch
thp-add-pmd_modify.patch
thp-mprotect-pass-vma-down-to-page-table-walkers.patch
thp-mprotect-transparent-huge-page-support.patch
thp-set-recommended-min-free-kbytes.patch
thp-enable-direct-defrag.patch
thp-add-numa-awareness-to-hugepage-allocations.patch
thp-allocate-memory-in-khugepaged-outside-of-mmap_sem-write-mode.patch
thp-transparent-hugepage-config-choice.patch
thp-select-config_compaction-if-transparent_hugepage-enabled.patch
thp-transhuge-isolate_migratepages.patch
thp-avoid-breaking-huge-pmd-invariants-in-case-of-vma_adjust-failures.patch
thp-dont-allow-transparent-hugepage-support-without-pse.patch
thp-mmu_notifier_test_young.patch
thp-freeze-khugepaged-and-ksmd.patch
thp-use-compaction-in-kswapd-for-gfp_atomic-order-0.patch
thp-use-compaction-for-all-allocation-orders.patch
thp-disable-transparent-hugepages-by-default-on-small-systems.patch
thp-fix-anon-memory-statistics-with-transparent-hugepages.patch
thp-scale-nr_rotated-to-balance-memory-pressure.patch
thp-transparent-hugepage-sysfs-meminfo.patch
thp-add-debug-checks-for-mapcount-related-invariants.patch
thp-fix-memory-failure-hugetlbfs-vs-thp-collision.patch
thp-compound_trans_order.patch
thp-mm-define-madv_nohugepage.patch
thp-madvisemadv_nohugepage.patch
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2010-12-15 23:57 + thp-allocate-memory-in-khugepaged-outside-of-mmap_sem-write-mode.patch added to -mm tree akpm
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