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 wJrBfK/b 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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: On 10/05/23 23:59, riel@surriel.com wrote: > From: Rik van Riel > > Malloc libraries, like jemalloc and tcalloc, take decisions on when > to call madvise independently from the code in the main application. > > This sometimes results in the application page faulting on an address, > right after the malloc library has shot down the backing memory with > MADV_DONTNEED. > > Usually this is harmless, because we always have some 4kB pages > sitting around to satisfy a page fault. However, with hugetlbfs > systems often allocate only the exact number of huge pages that > the application wants. > > Due to TLB batching, hugetlbfs MADV_DONTNEED will free pages outside of > any lock taken on the page fault path, which can open up the following > race condition: > > CPU 1 CPU 2 > > MADV_DONTNEED > unmap page > shoot down TLB entry > page fault > fail to allocate a huge page > killed with SIGBUS > free page > > Fix that race by pulling the locking from __unmap_hugepage_final_range > into helper functions called from zap_page_range_single. This ensures > page faults stay locked out of the MADV_DONTNEED VMA until the > huge pages have actually been freed. > > Signed-off-by: Rik van Riel > Cc: stable@kernel.org > Fixes: 04ada095dcfc ("hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing") > --- > include/linux/hugetlb.h | 35 +++++++++++++++++++++++++++++++++-- > mm/hugetlb.c | 34 ++++++++++++++++++++++------------ > mm/memory.c | 13 ++++++++----- > 3 files changed, 63 insertions(+), 19 deletions(-) Thanks for all the revisions, Reviewed-by: Mike Kravetz -- Mike Kravetz