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 LUrY4DdA 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 11/27/23 16:46, Muchun Song wrote: > The 8782fb61cc848 ("mm: pagewalk: Fix race between unmap and page walker") > introduces an assertion to walk_page_range_novma() to make all the users > of page table walker is safe. However, the race only exists for walking the > user page tables. And it is ridiculous to hold a particular user mmap write > lock against the changes of the kernel page tables. So only assert at least > mmap read lock when walking the kernel page tables. And some users matching > this case could downgrade to a mmap read lock to relief the contention of > mmap lock of init_mm, it will be nicer in hugetlb (only holding mmap read > lock) in the next patch. At first, I did not understand your motivation for this patch. But, it makes sense as your next patch will replace hugetlb vmemmap specific walk routines with walk_page_range_novma. Directly Cc'ing Steven and Jann in case they have comments. > > Signed-off-by: Muchun Song > --- > mm/pagewalk.c | 29 ++++++++++++++++++++++++++++- > 1 file changed, 28 insertions(+), 1 deletion(-) Looks fine to me, Acked-by: Mike Kravetz -- Mike Kravetz