[RESEND RFC PATCH v1 04/20] mm: invoke madvise for all vmas in scan_get_next_rmap_item
From: Stefan Roesch <hidden>
Date: 2023-01-23 17:59:28
Also in:
linux-doc, linux-fsdevel, linux-kselftest, linux-mm, lkml
Subsystem:
memory management, memory management - ksm (kernel samepage merging), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
If the new flag MMF_VM_MERGE_ANY has been set for a process, iterate over all the vmas and enable ksm if possible. For the vmas that can be ksm enabled this is only done once. Signed-off-by: Stefan Roesch <redacted> --- mm/ksm.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index 83796328574c..967eda719fab 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c@@ -1013,6 +1013,7 @@ static int unmerge_and_remove_all_rmap_items(void) mm_slot_free(mm_slot_cache, mm_slot); clear_bit(MMF_VM_MERGEABLE, &mm->flags); + clear_bit(MMF_VM_MERGE_ANY, &mm->flags); mmdrop(mm); } else spin_unlock(&ksm_mmlist_lock);
@@ -2243,6 +2244,17 @@ static struct ksm_rmap_item *get_next_rmap_item(struct ksm_mm_slot *mm_slot, return rmap_item; } +static bool vma_ksm_mergeable(struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_MERGEABLE) + return true; + + if (test_bit(MMF_VM_MERGE_ANY, &vma->vm_mm->flags)) + return true; + + return false; +} + static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) { struct mm_struct *mm;
@@ -2319,8 +2331,20 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) goto no_vmas; for_each_vma(vmi, vma) { - if (!(vma->vm_flags & VM_MERGEABLE)) + if (!vma_ksm_mergeable(vma)) continue; + if (!(vma->vm_flags & VM_MERGEABLE)) { + unsigned long flags = vma->vm_flags; + + /* madvise failed, use next vma */ + if (ksm_madvise(vma, vma->vm_start, vma->vm_end, MADV_MERGEABLE, &flags)) + continue; + /* vma, not supported as being mergeable */ + if (!(flags & VM_MERGEABLE)) + continue; + + vma->vm_flags = flags; + } if (ksm_scan.address < vma->vm_start) ksm_scan.address = vma->vm_start; if (!vma->anon_vma)
@@ -2389,6 +2413,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) mm_slot_free(mm_slot_cache, mm_slot); clear_bit(MMF_VM_MERGEABLE, &mm->flags); + clear_bit(MMF_VM_MERGE_ANY, &mm->flags); mmap_read_unlock(mm); mmdrop(mm); } else {
--
2.30.2