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authorZach O'Keefe <zokeefe@google.com>2022-07-07 02:59:25 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-09-12 06:25:45 +0300
commita7f4e6e4c47c41869fe5bea17e013b5557c57ed3 (patch)
treeae84db28379c4de278e961954e9199d5578ca8a9 /mm/khugepaged.c
parentd8ea7cc8547ca3f4962cfd114e4db11128587003 (diff)
downloadlinux-a7f4e6e4c47c41869fe5bea17e013b5557c57ed3.tar.xz
mm/thp: add flag to enforce sysfs THP in hugepage_vma_check()
MADV_COLLAPSE is not coupled to the kernel-oriented sysfs THP settings[1]. hugepage_vma_check() is the authority on determining if a VMA is eligible for THP allocation/collapse, and currently enforces the sysfs THP settings. Add a flag to disable these checks. For now, only apply this arg to anon and file, which use /sys/kernel/transparent_hugepage/enabled. We can expand this to shmem, which uses /sys/kernel/transparent_hugepage/shmem_enabled, later. Use this flag in collapse_pte_mapped_thp() where previously the VMA flags passed to hugepage_vma_check() were OR'd with VM_HUGEPAGE to elide the VM_HUGEPAGE check in "madvise" THP mode. Prior to "mm: khugepaged: check THP flag in hugepage_vma_check()", this check also didn't check "never" THP mode. As such, this restores the previous behavior of collapse_pte_mapped_thp() where sysfs THP settings are ignored. See comment in code for justification why this is OK. [1] https://lore.kernel.org/linux-mm/CAAa6QmQxay1_=Pmt8oCX2-Va18t44FV-Vs-WsQt_6+qBks4nZA@mail.gmail.com/ Link: https://lkml.kernel.org/r/20220706235936.2197195-8-zokeefe@google.com Signed-off-by: Zach O'Keefe <zokeefe@google.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Chris Kennelly <ckennelly@google.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Helge Deller <deller@gmx.de> Cc: Hugh Dickins <hughd@google.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavel Begunkov <asml.silence@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <songliubraving@fb.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <ziy@nvidia.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
-rw-r--r--mm/khugepaged.c25
1 files changed, 14 insertions, 11 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4661441375ea..af25206705aa 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -478,7 +478,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
{
if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
hugepage_flags_enabled()) {
- if (hugepage_vma_check(vma, vm_flags, false, false))
+ if (hugepage_vma_check(vma, vm_flags, false, false, true))
__khugepaged_enter(vma->vm_mm);
}
}
@@ -848,7 +848,8 @@ static bool khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node)
*/
static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
- struct vm_area_struct **vmap)
+ struct vm_area_struct **vmap,
+ struct collapse_control *cc)
{
struct vm_area_struct *vma;
@@ -861,7 +862,8 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
if (!transhuge_vma_suitable(vma, address))
return SCAN_ADDRESS_RANGE;
- if (!hugepage_vma_check(vma, vma->vm_flags, false, false))
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false,
+ cc->is_khugepaged))
return SCAN_VMA_CHECK;
/*
* Anon VMA expected, the address may be unmapped then
@@ -980,7 +982,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
goto out_nolock;
mmap_read_lock(mm);
- result = hugepage_vma_revalidate(mm, address, &vma);
+ result = hugepage_vma_revalidate(mm, address, &vma, cc);
if (result != SCAN_SUCCEED) {
mmap_read_unlock(mm);
goto out_nolock;
@@ -1012,7 +1014,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
* handled by the anon_vma lock + PG_lock.
*/
mmap_write_lock(mm);
- result = hugepage_vma_revalidate(mm, address, &vma);
+ result = hugepage_vma_revalidate(mm, address, &vma, cc);
if (result != SCAN_SUCCEED)
goto out_up_write;
/* check if the pmd is still valid */
@@ -1360,12 +1362,13 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
return;
/*
- * This vm_flags may not have VM_HUGEPAGE if the page was not
- * collapsed by this mm. But we can still collapse if the page is
- * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()
- * will not fail the vma for missing VM_HUGEPAGE
+ * If we are here, we've succeeded in replacing all the native pages
+ * in the page cache with a single hugepage. If a mm were to fault-in
+ * this memory (mapped by a suitably aligned VMA), we'd get the hugepage
+ * and map it by a PMD, regardless of sysfs THP settings. As such, let's
+ * analogously elide sysfs THP settings here.
*/
- if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false, false))
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false))
return;
/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2048,7 +2051,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
progress++;
break;
}
- if (!hugepage_vma_check(vma, vma->vm_flags, false, false)) {
+ if (!hugepage_vma_check(vma, vma->vm_flags, false, false, true)) {
skip:
progress++;
continue;