+ selftests-uevent-filtering-dont-shrink-the-socket-buffer.patch added to mm-nonmm-unstable branch

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

The patch titled
     Subject: selftests: uevent filtering: don't shrink the socket buffer
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     selftests-uevent-filtering-dont-shrink-the-socket-buffer.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-uevent-filtering-dont-shrink-the-socket-buffer.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Maximilian Heyne <mheyne@amazon.de>
Subject: selftests: uevent filtering: don't shrink the socket buffer
Date: Fri, 19 Jun 2026 11:24:29 +0000

The uevent_filtering test shrinks the uevent socket buffer to 4 KB
although the default socket buffer size is much higher.  This leads to
this test being flaky when too many unrelated uevents are fired on the
machine.  They might fill up the netlink receive buffer leading to ENOBUFS
errors when trying to receive the uevents.  For example, I could trigger
test failures when running triggering a lot of udev events in the
background:

  $ # run multiple of that in the background:
  $ while :; do sudo udevadm trigger --action=change; done &
  $ sudo ./uevent_filtering
    # Starting 1 tests from 1 test cases.
    #  RUN           global.uevent_filtering ...
    add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=304458
    add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=304471
    add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=304481
    add@/devices/virtual/mem/fullACTION=addDEVPATH=/devices/virtual/mem/fullSUBSYSTEM=memSYNTH_UUID=0MAJOR=1MINOR=7DEVNAME=fullDEVMODE=0666SEQNUM=349156
    No buffer space available - Failed to receive uevent
    # uevent_filtering.c:463:uevent_filtering:Expected 0 (0) == ret (-1)
    # uevent_filtering: Test failed
    #          FAIL  global.uevent_filtering
    not ok 1 global.uevent_filtering

The default receive buffer size (SK_RMEM_MAX) is far larger than the
requested 4 KB, so keep this to make the test less flaky.

Link: https://lore.kernel.org/20260619-get-swam-a1cd4cca@mheyne-amazon
Fixes: 9d3df886d17b ("selftests: uevent filtering")
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Cc: Christian Brauner <christianvanbrauner@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/uevent/uevent_filtering.c |    8 --------
 1 file changed, 8 deletions(-)

--- a/tools/testing/selftests/uevent/uevent_filtering.c~selftests-uevent-filtering-dont-shrink-the-socket-buffer
+++ a/tools/testing/selftests/uevent/uevent_filtering.c
@@ -78,7 +78,6 @@ static int uevent_listener(unsigned long
 {
 	int sk_fd, ret;
 	socklen_t sk_addr_len;
-	int rcv_buf_sz = __UEVENT_BUFFER_SIZE;
 	uint64_t sync_add = 1;
 	struct sockaddr_nl sk_addr = { 0 }, rcv_addr = { 0 };
 	char buf[__UEVENT_BUFFER_SIZE] = { 0 };
@@ -96,13 +95,6 @@ static int uevent_listener(unsigned long
 		return -1;
 	}
 
-	ret = setsockopt(sk_fd, SOL_SOCKET, SO_RCVBUF, &rcv_buf_sz,
-			 sizeof(rcv_buf_sz));
-	if (ret < 0) {
-		fprintf(stderr, "%s - Failed to set socket options\n", strerror(errno));
-		goto on_error;
-	}
-
 	sk_addr.nl_family = AF_NETLINK;
 	sk_addr.nl_groups = __UEVENT_LISTEN_ALL;
 
_

Patches currently in -mm which might be from mheyne@amazon.de are

selftests-uevent-filtering-dont-shrink-the-socket-buffer.patch