From 4000e3d0a367c5ff2035a0394b01b93974be6cb1 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Wed, 5 Feb 2025 22:15:17 -0800 Subject: [PATCH] mm/madvise: remove redundant mmap_lock operations from process_madvise() Optimize redundant mmap lock operations from process_madvise() by directly doing the mmap locking first, and then the remaining works for all ranges in the loop. [akpm@linux-foundation.org: update comment, per Lorenzo] Link: https://lkml.kernel.org/r/20250206061517.2958-5-sj@kernel.org Signed-off-by: SeongJae Park Reviewed-by: Shakeel Butt Reviewed-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Cc: David Hildenbrand Cc: Davidlohr Bueso Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/madvise.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index 6e31e3202d71..6ecead476a80 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1778,16 +1778,33 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter, total_len = iov_iter_count(iter); + ret = madvise_lock(mm, behavior); + if (ret) + return ret; + while (iov_iter_count(iter)) { - ret = do_madvise(mm, (unsigned long)iter_iov_addr(iter), - iter_iov_len(iter), behavior); + unsigned long start = (unsigned long)iter_iov_addr(iter); + size_t len_in = iter_iov_len(iter); + size_t len; + + if (!is_valid_madvise(start, len_in, behavior)) { + ret = -EINVAL; + break; + } + + len = PAGE_ALIGN(len_in); + if (start + len == start) + ret = 0; + else + ret = madvise_do_behavior(mm, start, len_in, len, + behavior); /* * An madvise operation is attempting to restart the syscall, * but we cannot proceed as it would not be correct to repeat * the operation in aggregate, and would be surprising to the * user. * - * As we have already dropped locks, it is safe to just loop and + * We drop and reacquire locks so it is safe to just loop and * try again. We check for fatal signals in case we need exit * early anyway. */ @@ -1796,12 +1813,17 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter, ret = -EINTR; break; } + + /* Drop and reacquire lock to unwind race. */ + madvise_unlock(mm, behavior); + madvise_lock(mm, behavior); continue; } if (ret < 0) break; iov_iter_advance(iter, iter_iov_len(iter)); } + madvise_unlock(mm, behavior); ret = (total_len - iov_iter_count(iter)) ? : ret; -- 2.25.1