[to-be-updated] mm-madvise-reject-invalid-process_madvise-advice-for-zero-length-vectors.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/madvise: reject invalid process_madvise() advice for zero-length vectors
has been removed from the -mm tree.  Its filename was
     mm-madvise-reject-invalid-process_madvise-advice-for-zero-length-vectors.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: fujunjie <fujunjie1@qq.com>
Subject: mm/madvise: reject invalid process_madvise() advice for zero-length vectors
Date: Mon, 27 Apr 2026 09:43:30 +0000

process_madvise() used to validate the advice while walking each imported
iovec.  If the vector has zero total length, vector_madvise() does not
enter the loop and can return success without checking whether the advice
value is valid.

For a local mm, such as process_madvise(PIDFD_SELF, ...), the remote-only
process_madvise_remote_valid() check is skipped.  As a result, an invalid
advice can be reported as success when the vector has zero total length. 
This differs from madvise(), which rejects an invalid advice before
returning success for a zero-length range.

Validate the generic madvise behavior at the syscall-facing entry points
before any vector walk.  In process_madvise(), do this before the
remote-only advice restriction so unsupported advice is rejected with the
same priority for local and remote mm.  Then keep the per-range helper
focused on address/length validation, avoiding repeated behavior checks
for every iovec.

Valid zero-length requests remain no-ops and continue to return 0.  Add a
selftest that covers invalid advice with a zero-length iovec and an empty
vector, while also checking that a valid zero-length request still
succeeds.

Link: https://lore.kernel.org/tencent_BB588C2CDED859A873093DAF28B2CC1F7B0A@qq.com
Fixes: 021781b01275 ("mm/madvise: unrestrict process_madvise() for current process")
Signed-off-by: fujunjie <fujunjie1@qq.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/madvise.c                              |   29 +++++++++++---------
 tools/testing/selftests/mm/process_madv.c |   29 ++++++++++++++++++++
 2 files changed, 45 insertions(+), 13 deletions(-)

--- a/mm/madvise.c~mm-madvise-reject-invalid-process_madvise-advice-for-zero-length-vectors
+++ a/mm/madvise.c
@@ -1834,13 +1834,10 @@ static void madvise_finish_tlb(struct ma
 		tlb_finish_mmu(madv_behavior->tlb);
 }
 
-static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior)
+static bool is_valid_madvise_range(unsigned long start, size_t len_in)
 {
 	size_t len;
 
-	if (!madvise_behavior_valid(behavior))
-		return false;
-
 	if (!PAGE_ALIGNED(start))
 		return false;
 	len = PAGE_ALIGN(len_in);
@@ -1859,17 +1856,15 @@ static bool is_valid_madvise(unsigned lo
  * madvise_should_skip() - Return if the request is invalid or nothing.
  * @start:	Start address of madvise-requested address range.
  * @len_in:	Length of madvise-requested address range.
- * @behavior:	Requested madvise behavior.
  * @err:	Pointer to store an error code from the check.
  *
- * If the specified behaviour is invalid or nothing would occur, we skip the
- * operation.  This function returns true in the cases, otherwise false.  In
- * the former case we store an error on @err.
+ * If the specified range is invalid or nothing would occur, we skip the
+ * operation.  This function returns true in these cases, otherwise false.  In
+ * the former case we store an error in @err.
  */
-static bool madvise_should_skip(unsigned long start, size_t len_in,
-		int behavior, int *err)
+static bool madvise_should_skip(unsigned long start, size_t len_in, int *err)
 {
-	if (!is_valid_madvise(start, len_in, behavior)) {
+	if (!is_valid_madvise_range(start, len_in)) {
 		*err = -EINVAL;
 		return true;
 	}
@@ -2013,7 +2008,10 @@ int do_madvise(struct mm_struct *mm, uns
 		.tlb = &tlb,
 	};
 
-	if (madvise_should_skip(start, len_in, behavior, &error))
+	if (!madvise_behavior_valid(behavior))
+		return -EINVAL;
+
+	if (madvise_should_skip(start, len_in, &error))
 		return error;
 	error = madvise_lock(&madv_behavior);
 	if (error)
@@ -2056,7 +2054,7 @@ static ssize_t vector_madvise(struct mm_
 		size_t len_in = iter_iov_len(iter);
 		int error;
 
-		if (madvise_should_skip(start, len_in, behavior, &error))
+		if (madvise_should_skip(start, len_in, &error))
 			ret = error;
 		else
 			ret = madvise_do_behavior(start, len_in, &madv_behavior);
@@ -2131,6 +2129,11 @@ SYSCALL_DEFINE5(process_madvise, int, pi
 		goto release_task;
 	}
 
+	if (!madvise_behavior_valid(behavior)) {
+		ret = -EINVAL;
+		goto release_mm;
+	}
+
 	/*
 	 * We need only perform this check if we are attempting to manipulate a
 	 * remote process's address space.
--- a/tools/testing/selftests/mm/process_madv.c~mm-madvise-reject-invalid-process_madvise-advice-for-zero-length-vectors
+++ a/tools/testing/selftests/mm/process_madv.c
@@ -310,6 +310,35 @@ TEST_F(process_madvise, invalid_vlen)
 }
 
 /*
+ * Test that invalid advice is rejected even when the iovec has zero total
+ * length. A zero-length advice is a no-op for valid advice, but invalid
+ * advice should still fail with EINVAL.
+ */
+TEST_F(process_madvise, invalid_advice_zero_length)
+{
+	struct iovec vec = {
+		.iov_base = NULL,
+		.iov_len = 0,
+	};
+	int pidfd = self->pidfd;
+	ssize_t ret;
+
+	errno = 0;
+	ret = sys_process_madvise(pidfd, &vec, 1, -1, 0);
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, EINVAL);
+
+	errno = 0;
+	ret = sys_process_madvise(pidfd, &vec, 1, MADV_DONTNEED, 0);
+	ASSERT_EQ(ret, 0);
+
+	errno = 0;
+	ret = sys_process_madvise(pidfd, NULL, 0, -1, 0);
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, EINVAL);
+}
+
+/*
  * Test process_madvise() with an invalid flag value. Currently, only a flag
  * value of 0 is supported. This test is reserved for the future, e.g., if
  * synchronous flags are added.
_

Patches currently in -mm which might be from fujunjie1@qq.com are

mm-filemap-count-only-the-faulting-address-as-a-mmap-hit.patch
mm-filemap-do-not-count-fault_flag_tried-retries-as-mmap-hits.patch