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([157.51.37.214]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a93397ef6fsm27170315ad.95.2026.02.04.06.24.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Feb 2026 06:24:13 -0800 (PST) From: Aswin Kumar To: linux-mm@kvack.org Cc: andrew.morton@linux-foundation.org, linux-kernel@vger.kernel.org, Aswin Kumar Subject: [PATCH] mm/userfaultfd: fix likely/unlikely annotation in move_pages() Date: Wed, 4 Feb 2026 14:23:50 +0000 Message-ID: <20260204142350.1642-1-aswinkumar3301@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" All other userfaultfd paths use unlikely() for the mmap_changing check, since normally mmap is not changing. The move_pages() path incorrectly uses likely(), which is the opposite of the intended branch prediction hint. This is a performance-only fix - the logic is correct but the branch prediction annotation is wrong, potentially causing a minor performance penalty on the fast path. Fixes: e0a58ef0faa7 ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Aswin Kumar --- mm/userfaultfd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index e6dfd5f28..d27080348 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1793,7 +1793,7 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsig= ned long dst_start, /* Re-check after taking map_changing_lock */ err =3D -EAGAIN; down_read(&ctx->map_changing_lock); - if (likely(atomic_read(&ctx->mmap_changing))) + if (unlikely(atomic_read(&ctx->mmap_changing))) goto out_unlock; /* * Make sure the vma is not shared, that the src and dst remap --=20 2.43.0