On 6/5/24 5:56 PM, David Hildenbrand wrote: > On 05.06.24 11:53, alexs@xxxxxxxxxx wrote: >> From: "Alex Shi (tencent)" <alexs@xxxxxxxxxx> >> >> We do vma_set_anonyous in do_mmap(), and then vma_is_anonymous() >> checking workable, use it as a extra check since ksm only care anonymous >> pages. >> >> Signed-off-by: Alex Shi (tencent) <alexs@xxxxxxxxxx> >> --- >> mm/ksm.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/mm/ksm.c b/mm/ksm.c >> index f5138f43f0d2..088bce39cd33 100644 >> --- a/mm/ksm.c >> +++ b/mm/ksm.c >> @@ -742,7 +742,8 @@ static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm, >> if (ksm_test_exit(mm)) >> return NULL; >> vma = vma_lookup(mm, addr); >> - if (!vma || !(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma) >> + if (!vma || !(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma || >> + !vma_is_anonymous(vma)) > > Doesn't KSM also apply to COW'ed pages in !anon mappings? At least that's what I recall. I didn't a evidence for this. :( In write_protect_page(), "PageAnonExclusive(&folio->page);" has a "VM_BUG_ON_PGFLAGS(!PageAnon(page), page);" So is this hints the vma also need to be anonymous one? Thanks a lot! Alex >
