Patch "selftests: secretmem: floor the memory size to the multiple of page_size" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    selftests: secretmem: floor the memory size to the multiple of page_size

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-secretmem-floor-the-memory-size-to-the-mul.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d7ad4df13708de4f4efc488d7afaf6d358a548c6
Author: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Date:   Thu Dec 14 15:19:30 2023 +0500

    selftests: secretmem: floor the memory size to the multiple of page_size
    
    [ Upstream commit 0aac13add26d546ac74c89d2883b3a5f0fbea039 ]
    
    The "locked-in-memory size" limit per process can be non-multiple of
    page_size.  The mmap() fails if we try to allocate locked-in-memory with
    same size as the allowed limit if it isn't multiple of the page_size
    because mmap() rounds off the memory size to be allocated to next multiple
    of page_size.
    
    Fix this by flooring the length to be allocated with mmap() to the
    previous multiple of the page_size.
    
    This was getting triggered on KernelCI regularly because of different
    ulimit settings which wasn't multiple of the page_size.  Find logs
    here: https://linux.kernelci.org/test/plan/id/657654bd8e81e654fae13532/
    The bug in was present from the time test was first added.
    
    Link: https://lkml.kernel.org/r/20231214101931.1155586-1-usama.anjum@xxxxxxxxxxxxx
    Fixes: 76fe17ef588a ("secretmem: test: add basic selftest for memfd_secret(2)")
    Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
    Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx>
    Closes: https://linux.kernelci.org/test/plan/id/657654bd8e81e654fae13532/
    Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
    Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
    Cc: Shuah Khan <shuah@xxxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx>
    Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/vm/memfd_secret.c b/tools/testing/selftests/vm/memfd_secret.c
index 93e7e7ffed337..9177490981489 100644
--- a/tools/testing/selftests/vm/memfd_secret.c
+++ b/tools/testing/selftests/vm/memfd_secret.c
@@ -62,6 +62,9 @@ static void test_mlock_limit(int fd)
 	char *mem;
 
 	len = mlock_limit_cur;
+	if (len % page_size != 0)
+		len = (len/page_size) * page_size;
+
 	mem = mmap(NULL, len, prot, mode, fd, 0);
 	if (mem == MAP_FAILED) {
 		fail("unable to mmap secret memory\n");