Until CONFIG_DMABUF_SYSFS_STATS was added [1] it was only possible to
perform per-buffer accounting with debugfs which is not suitable for
production environments. Eventually we discovered the overhead with
per-buffer sysfs file creation/removal was significantly impacting
allocation and free times, and exacerbated kernfs lock contention. [2]
dma_buf_stats_setup() is responsible for 39% of single-page buffer
creation duration, or 74% of single-page dma_buf_export() duration when
stressing dmabuf allocations and frees.
I prototyped a change from per-buffer to per-exporter statistics with a
RCU protected list of exporter allocations that accommodates most (but
not all) of our use-cases and avoids almost all of the sysfs overhead.
While that adds less overhead than per-buffer sysfs, and less even than
the maintenance of the dmabuf debugfs_list, it's still *additional*
overhead on top of the debugfs_list and doesn't give us per-buffer info.
This series uses the existing dmabuf debugfs_list to implement a BPF
dmabuf iterator, which adds no overhead to buffer allocation/free and
provides per-buffer info. The list has been moved outside of
CONFIG_DEBUG_FS scope so that it is always populated. The BPF program
loaded by userspace that extracts per-buffer information gets to define
its own interface which avoids the lack of ABI stability with debugfs.
As this is a replacement for our use of CONFIG_DMABUF_SYSFS_STATS, the
last patch is a RFC for removing it from the kernel. Please see my
suggestion there regarding the timeline for that.
[1] https://lore.kernel.org/linux-media/20201210044400.1080308-1-hridya@google.…
[2] https://lore.kernel.org/all/20220516171315.2400578-1-tjmercier@google.com
v1: https://lore.kernel.org/all/20250414225227.3642618-1-tjmercier@google.com
v1 -> v2:
Make the DMA buffer list independent of CONFIG_DEBUG_FS per Christian König
Add CONFIG_DMA_SHARED_BUFFER check to kernel/bpf/Makefile per kernel test robot
Use BTF_ID_LIST_SINGLE instead of BTF_ID_LIST_GLOBAL_SINGLE per Song Liu
Fixup comment style, mixing code/declarations, and use ASSERT_OK_FD in selftest per Song Liu
Add BPF_ITER_RESCHED feature to bpf_dmabuf_reg_info per Alexei Starovoitov
Add open-coded iterator and selftest per Alexei Starovoitov
Add a second test buffer from the system dmabuf heap to selftests
Use the BPF program we'll use in production for selftest per Alexei Starovoitov
https://r.android.com/c/platform/system/bpfprogs/+/3616123/2/dmabufIter.chttps://r.android.com/c/platform/system/memory/libmeminfo/+/3614259/1/libdm…
T.J. Mercier (6):
dma-buf: Rename and expose debugfs symbols
bpf: Add dmabuf iterator
bpf: Add open coded dmabuf iterator
selftests/bpf: Add test for dmabuf_iter
selftests/bpf: Add test for open coded dmabuf_iter
RFC: dma-buf: Remove DMA-BUF statistics
.../ABI/testing/sysfs-kernel-dmabuf-buffers | 24 --
Documentation/driver-api/dma-buf.rst | 5 -
drivers/dma-buf/Kconfig | 15 -
drivers/dma-buf/Makefile | 1 -
drivers/dma-buf/dma-buf-sysfs-stats.c | 202 --------------
drivers/dma-buf/dma-buf-sysfs-stats.h | 35 ---
drivers/dma-buf/dma-buf.c | 58 +---
include/linux/dma-buf.h | 6 +-
kernel/bpf/Makefile | 3 +
kernel/bpf/dmabuf_iter.c | 177 ++++++++++++
kernel/bpf/helpers.c | 5 +
.../testing/selftests/bpf/bpf_experimental.h | 5 +
tools/testing/selftests/bpf/config | 3 +
.../selftests/bpf/prog_tests/dmabuf_iter.c | 258 ++++++++++++++++++
.../testing/selftests/bpf/progs/dmabuf_iter.c | 91 ++++++
15 files changed, 561 insertions(+), 327 deletions(-)
delete mode 100644 Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
delete mode 100644 drivers/dma-buf/dma-buf-sysfs-stats.c
delete mode 100644 drivers/dma-buf/dma-buf-sysfs-stats.h
create mode 100644 kernel/bpf/dmabuf_iter.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c
create mode 100644 tools/testing/selftests/bpf/progs/dmabuf_iter.c
base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
--
2.49.0.906.g1f30a19c02-goog
From: Brendan Jackman <jackmanb(a)google.com>
[ Upstream commit 08fafac4c9f289a9d9a22d838921e4b3eb22c664 ]
As noted in [0], SeaBIOS (QEMU default) makes a mess of the terminal,
qboot does not.
It turns out this is actually useful with kunit.py, since the user is
exposed to this issue if they set --raw_output=all.
qboot is also faster than SeaBIOS, but it's is marginal for this
usecase.
[0] https://lore.kernel.org/all/CA+i-1C0wYb-gZ8Mwh3WSVpbk-LF-Uo+njVbASJPe1WXDUR…
Both SeaBIOS and qboot are x86-specific.
Link: https://lore.kernel.org/r/20250124-kunit-qboot-v1-1-815e4d4c6f7c@google.com
Signed-off-by: Brendan Jackman <jackmanb(a)google.com>
Reviewed-by: David Gow <davidgow(a)google.com>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/kunit/qemu_configs/x86_64.py | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/testing/kunit/qemu_configs/x86_64.py b/tools/testing/kunit/qemu_configs/x86_64.py
index dc79490768630..4a6bf4e048f5b 100644
--- a/tools/testing/kunit/qemu_configs/x86_64.py
+++ b/tools/testing/kunit/qemu_configs/x86_64.py
@@ -7,4 +7,6 @@ CONFIG_SERIAL_8250_CONSOLE=y''',
qemu_arch='x86_64',
kernel_path='arch/x86/boot/bzImage',
kernel_command_line='console=ttyS0',
- extra_qemu_params=[])
+ # qboot is faster than SeaBIOS and doesn't mess up
+ # the terminal.
+ extra_qemu_params=['-bios', 'qboot.rom'])
--
2.39.5
From: Petr Machata <petrm(a)nvidia.com>
[ Upstream commit d9e9f6d7b7d0c520bb87f19d2cbc57aeeb2091d5 ]
Attempts to replace an MDB group membership of the host itself are
currently bounced:
# ip link add name br up type bridge vlan_filtering 1
# bridge mdb replace dev br port br grp 239.0.0.1 vid 2
# bridge mdb replace dev br port br grp 239.0.0.1 vid 2
Error: bridge: Group is already joined by host.
A similar operation done on a member port would succeed. Ignore the check
for replacement of host group memberships as well.
The bit of code that this enables is br_multicast_host_join(), which, for
already-joined groups only refreshes the MC group expiration timer, which
is desirable; and a userspace notification, also desirable.
Change a selftest that exercises this code path from expecting a rejection
to expecting a pass. The rest of MDB selftests pass without modification.
Signed-off-by: Petr Machata <petrm(a)nvidia.com>
Reviewed-by: Ido Schimmel <idosch(a)nvidia.com>
Acked-by: Nikolay Aleksandrov <razor(a)blackwall.org>
Link: https://patch.msgid.link/e5c5188b9787ae806609e7ca3aa2a0a501b9b5c4.173868564…
Signed-off-by: Jakub Kicinski <kuba(a)kernel.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
net/bridge/br_mdb.c | 2 +-
tools/testing/selftests/net/forwarding/bridge_mdb.sh | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 7305f5f8215ca..96bea0c8408fe 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -1030,7 +1030,7 @@ static int br_mdb_add_group(const struct br_mdb_config *cfg,
/* host join */
if (!port) {
- if (mp->host_joined) {
+ if (mp->host_joined && !(cfg->nlflags & NLM_F_REPLACE)) {
NL_SET_ERR_MSG_MOD(extack, "Group is already joined by host");
return -EEXIST;
}
diff --git a/tools/testing/selftests/net/forwarding/bridge_mdb.sh b/tools/testing/selftests/net/forwarding/bridge_mdb.sh
index a3678dfe5848a..c151374ddf040 100755
--- a/tools/testing/selftests/net/forwarding/bridge_mdb.sh
+++ b/tools/testing/selftests/net/forwarding/bridge_mdb.sh
@@ -149,7 +149,7 @@ cfg_test_host_common()
check_err $? "Failed to add $name host entry"
bridge mdb replace dev br0 port br0 grp $grp $state vid 10 &> /dev/null
- check_fail $? "Managed to replace $name host entry"
+ check_err $? "Failed to replace $name host entry"
bridge mdb del dev br0 port br0 grp $grp $state vid 10
bridge mdb get dev br0 grp $grp vid 10 &> /dev/null
--
2.39.5
Fix some more minor issues in ublk selftests.
The first patch is from
https://lore.kernel.org/linux-block/20250423-ublk_selftests-v1-0-7d060e260e…
with a modification requested by Jens. The others are new.
Signed-off-by: Uday Shankar <ushankar(a)purestorage.com>
---
Changes in v2:
- Use a test-specific WERROR flag instead of reusing CONFIG_WERROR from
the kernel build for deciding whether or not to use -Werror for the
kublk build. The default behavior is to use -Werror (Ming Lei)
- Link to v1: https://lore.kernel.org/r/20250428-ublk_selftests-v1-0-5795f7b00cda@puresto…
---
Uday Shankar (3):
selftests: ublk: kublk: build with -Werror iff WERROR!=0
selftests: ublk: make test_generic_06 silent on success
selftests: ublk: kublk: fix include path
tools/testing/selftests/ublk/Makefile | 6 +++++-
tools/testing/selftests/ublk/kublk.h | 1 -
tools/testing/selftests/ublk/test_generic_06.sh | 2 +-
3 files changed, 6 insertions(+), 3 deletions(-)
---
base-commit: 53ec1abce79c986dc59e59d0c60d00088bcdf32a
change-id: 20250428-ublk_selftests-983240d3a325
Best regards,
--
Uday Shankar <ushankar(a)purestorage.com>
From: Brendan Jackman <jackmanb(a)google.com>
[ Upstream commit 08fafac4c9f289a9d9a22d838921e4b3eb22c664 ]
As noted in [0], SeaBIOS (QEMU default) makes a mess of the terminal,
qboot does not.
It turns out this is actually useful with kunit.py, since the user is
exposed to this issue if they set --raw_output=all.
qboot is also faster than SeaBIOS, but it's is marginal for this
usecase.
[0] https://lore.kernel.org/all/CA+i-1C0wYb-gZ8Mwh3WSVpbk-LF-Uo+njVbASJPe1WXDUR…
Both SeaBIOS and qboot are x86-specific.
Link: https://lore.kernel.org/r/20250124-kunit-qboot-v1-1-815e4d4c6f7c@google.com
Signed-off-by: Brendan Jackman <jackmanb(a)google.com>
Reviewed-by: David Gow <davidgow(a)google.com>
Signed-off-by: Shuah Khan <skhan(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
tools/testing/kunit/qemu_configs/x86_64.py | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/testing/kunit/qemu_configs/x86_64.py b/tools/testing/kunit/qemu_configs/x86_64.py
index dc79490768630..4a6bf4e048f5b 100644
--- a/tools/testing/kunit/qemu_configs/x86_64.py
+++ b/tools/testing/kunit/qemu_configs/x86_64.py
@@ -7,4 +7,6 @@ CONFIG_SERIAL_8250_CONSOLE=y''',
qemu_arch='x86_64',
kernel_path='arch/x86/boot/bzImage',
kernel_command_line='console=ttyS0',
- extra_qemu_params=[])
+ # qboot is faster than SeaBIOS and doesn't mess up
+ # the terminal.
+ extra_qemu_params=['-bios', 'qboot.rom'])
--
2.39.5
Fix some more minor issues in ublk selftests.
The first patch is from
https://lore.kernel.org/linux-block/20250423-ublk_selftests-v1-0-7d060e260e…
with a modification requested by Jens. The others are new.
Signed-off-by: Uday Shankar <ushankar(a)purestorage.com>
---
Uday Shankar (3):
selftests: ublk: kublk: build with -Werror iff CONFIG_WERROR=y
selftests: ublk: make test_generic_06 silent on success
selftests: ublk: kublk: fix include path
tools/testing/selftests/ublk/Makefile | 4 +++-
tools/testing/selftests/ublk/kublk.h | 1 -
tools/testing/selftests/ublk/test_generic_06.sh | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)
---
base-commit: 53ec1abce79c986dc59e59d0c60d00088bcdf32a
change-id: 20250428-ublk_selftests-983240d3a325
Best regards,
--
Uday Shankar <ushankar(a)purestorage.com>