Currently if we request a feature that is not set in the Kernel
config we fail silently and return all the available features. However,
the man page indicates we should return an EINVAL.
We need to fix this issue since we can end up with a Kernel warning
should a program request the feature UFFD_FEATURE_WP_UNPOPULATED on
a kernel with the config not set with this feature.
[ 200.812896] WARNING: CPU: 91 PID: 13634 at mm/memory.c:1660 zap_pte_range+0x43d/0x660
[ 200.820738] Modules linked in:
[ 200.869387] CPU: 91 PID: 13634 Comm: userfaultfd Kdump: loaded Not tainted 6.9.0-rc5+ #8
[ 200.877477] Hardware name: Dell Inc. PowerEdge R6525/0N7YGH, BIOS 2.7.3 03/30/2022
[ 200.885052] RIP: 0010:zap_pte_range+0x43d/0x660
Fixes: e06f1e1dd499 ("userfaultfd: wp: enabled write protection in userfaultfd API")
Signed-off-by: Audra Mitchell <audra(a)redhat.com>
---
fs/userfaultfd.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index eee7320ab0b0..17e409ceaa33 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -2057,7 +2057,7 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
goto out;
features = uffdio_api.features;
ret = -EINVAL;
- if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES))
+ if (uffdio_api.api != UFFD_API)
goto err_out;
ret = -EPERM;
if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE))
@@ -2081,6 +2081,11 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED;
uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC;
#endif
+
+ ret = -EINVAL;
+ if (features & ~uffdio_api.features)
+ goto err_out;
+
uffdio_api.ioctls = UFFD_API_IOCTLS;
ret = -EFAULT;
if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
--
2.44.0
v13: https://patchwork.kernel.org/project/netdevbpf/list/?series=861406&archive=…
====
Major changes:
--------------
This iteration addresses Pavel's review comments, applies his
reviewed-by's, and seeks to fix the patchwork build error (sorry!).
As usual, the full devmem TCP changes including the full GVE driver
implementation is here:
https://github.com/mina/linux/commits/tcpdevmem-v13/
v12: https://patchwork.kernel.org/project/netdevbpf/list/?series=859747&state=*
====
Major changes:
--------------
This iteration only addresses one minor comment from Pavel with regards
to the trace printing of netmem, and the patchwork build error
introduced in v11 because I missed doing an allmodconfig build, sorry.
Other than that v11, AFAICT, received no feedback. There is one
discussion about how the specifics of plugging io uring memory through
the page pool, but not relevant to content in this particular patchset,
AFAICT.
As usual, the full devmem TCP changes including the full GVE driver
implementation is here:
https://github.com/mina/linux/commits/tcpdevmem-v12/
v11: https://patchwork.kernel.org/project/netdevbpf/list/?series=857457&state=*
====
Major Changes:
--------------
v11 addresses feedback received in v10. The major change is the removal
of the memory provider ops as requested by Christoph. We still
accomplish the same thing, but utilizing direct function calls with if
statements rather than generic ops.
Additionally address sparse warnings, bugs and review comments from
folks that reviewed.
As usual, the full devmem TCP changes including the full GVE driver
implementation is here:
https://github.com/mina/linux/commits/tcpdevmem-v11/
Detailed changelog:
-------------------
- Fixes in netdev_rx_queue_restart() from Pavel & David.
- Remove commit e650e8c3a36f5 ("net: page_pool: create hooks for
custom page providers") from the series to address Christoph's
feedback and rebased other patches on the series on this change.
- Fixed build errors with CONFIG_DMA_SHARED_BUFFER &&
!CONFIG_GENERIC_ALLOCATOR build.
- Fixed sparse warnings pointed out by Paolo.
- Drop unnecessary gro_pull_from_frag0 checks.
- Added Bagas reviewed-by to docs.
Cc: Bagas Sanjaya <bagasdotme(a)gmail.com>
Cc: Steven Rostedt <rostedt(a)goodmis.org>
Cc: Christoph Hellwig <hch(a)infradead.org>
Cc: Nikolay Aleksandrov <razor(a)blackwall.org>
v10: https://patchwork.kernel.org/project/netdevbpf/list/?series=852422&state=*
====
Major Changes:
--------------
v9 was sent right before the merge window closed (sorry!). v10 is almost
a re-send of the series now that the merge window re-opened. Only
rebased to latest net-next and addressed some minor iterative comments
received on v9.
As usual, the full devmem TCP changes including the full GVE driver
implementation is here:
https://github.com/mina/linux/commits/tcpdevmem-v10/
Detailed changelog:
-------------------
- Fixed tokens leaking in DONTNEED setsockopt (Nikolay).
- Moved net_iov_dma_addr() to devmem.c and made it a devmem specific
helpers (David).
- Rename hook alloc_pages to alloc_netmems as alloc_pages is now
preprocessor macro defined and causes a build error.
v9:
===
Major Changes:
--------------
GVE queue API has been merged. Submitting this version as non-RFC after
rebasing on top of the merged API, and dropped the out of tree queue API
I was carrying on github. Addressed the little feedback v8 has received.
Detailed changelog:
------------------
- Added new patch from David Wei to this series for
netdev_rx_queue_restart()
- Fixed sparse error.
- Removed CONFIG_ checks in netmem_is_net_iov()
- Flipped skb->readable to skb->unreadable
- Minor fixes to selftests & docs.
RFC v8:
=======
Major Changes:
--------------
- Fixed build error generated by patch-by-patch build.
- Applied docs suggestions from Randy.
RFC v7:
=======
Major Changes:
--------------
This revision largely rebases on top of net-next and addresses the feedback
RFCv6 received from folks, namely Jakub, Yunsheng, Arnd, David, & Pavel.
The series remains in RFC because the queue-API ndos defined in this
series are not yet implemented. I have a GVE implementation I carry out
of tree for my testing. A upstreamable GVE implementation is in the
works. Aside from that, in my estimation all the patches are ready for
review/merge. Please do take a look.
As usual the full devmem TCP changes including the full GVE driver
implementation is here:
https://github.com/mina/linux/commits/tcpdevmem-v7/
Detailed changelog:
- Use admin-perm in netlink API.
- Addressed feedback from Jakub with regards to netlink API
implementation.
- Renamed devmem.c functions to something more appropriate for that
file.
- Improve the performance seen through the page_pool benchmark.
- Fix the value definition of all the SO_DEVMEM_* uapi.
- Various fixes to documentation.
Perf - page-pool benchmark:
---------------------------
Improved performance of bench_page_pool_simple.ko tests compared to v6:
https://pastebin.com/raw/v5dYRg8L
net-next base: 8 cycle fast path.
RFC v6: 10 cycle fast path.
RFC v7: 9 cycle fast path.
RFC v7 with CONFIG_DMA_SHARED_BUFFER disabled: 8 cycle fast path,
same as baseline.
Perf - Devmem TCP benchmark:
---------------------
Perf is about the same regardless of the changes in v7, namely the
removal of the static_branch_unlikely to improve the page_pool benchmark
performance:
189/200gbps bi-directional throughput with RX devmem TCP and regular TCP
TX i.e. ~95% line rate.
RFC v6:
=======
Major Changes:
--------------
This revision largely rebases on top of net-next and addresses the little
feedback RFCv5 received.
The series remains in RFC because the queue-API ndos defined in this
series are not yet implemented. I have a GVE implementation I carry out
of tree for my testing. A upstreamable GVE implementation is in the
works. Aside from that, in my estimation all the patches are ready for
review/merge. Please do take a look.
As usual the full devmem TCP changes including the full GVE driver
implementation is here:
https://github.com/mina/linux/commits/tcpdevmem-v6/
This version also comes with some performance data recorded in the cover
letter (see below changelog).
Detailed changelog:
- Rebased on top of the merged netmem_ref changes.
- Converted skb->dmabuf to skb->readable (Pavel). Pavel's original
suggestion was to remove the skb->dmabuf flag entirely, but when I
looked into it closely, I found the issue that if we remove the flag
we have to dereference the shinfo(skb) pointer to obtain the first
frag to tell whether an skb is readable or not. This can cause a
performance regression if it dirties the cache line when the
shinfo(skb) was not really needed. Instead, I converted the skb->dmabuf
flag into a generic skb->readable flag which can be re-used by io_uring
0-copy RX.
- Squashed a few locking optimizations from Eric Dumazet in the RX path
and the DEVMEM_DONTNEED setsockopt.
- Expanded the tests a bit. Added validation for invalid scenarios and
added some more coverage.
Perf - page-pool benchmark:
---------------------------
bench_page_pool_simple.ko tests with and without these changes:
https://pastebin.com/raw/ncHDwAbn
AFAIK the number that really matters in the perf tests is the
'tasklet_page_pool01_fast_path Per elem'. This one measures at about 8
cycles without the changes but there is some 1 cycle noise in some
results.
With the patches this regresses to 9 cycles with the changes but there
is 1 cycle noise occasionally running this test repeatedly.
Lastly I tried disable the static_branch_unlikely() in
netmem_is_net_iov() check. To my surprise disabling the
static_branch_unlikely() check reduces the fast path back to 8 cycles,
but the 1 cycle noise remains.
Perf - Devmem TCP benchmark:
---------------------
189/200gbps bi-directional throughput with RX devmem TCP and regular TCP
TX i.e. ~95% line rate.
Major changes in RFC v5:
========================
1. Rebased on top of 'Abstract page from net stack' series and used the
new netmem type to refer to LSB set pointers instead of re-using
struct page.
2. Downgraded this series back to RFC and called it RFC v5. This is
because this series is now dependent on 'Abstract page from net
stack'[1] and the queue API. Both are removed from the series to
reduce the patch # and those bits are fairly independent or
pre-requisite work.
3. Reworked the page_pool devmem support to use netmem and for some
more unified handling.
4. Reworked the reference counting of net_iov (renamed from
page_pool_iov) to use pp_ref_count for refcounting.
The full changes including the dependent series and GVE page pool
support is here:
https://github.com/mina/linux/commits/tcpdevmem-rfcv5/
[1] https://patchwork.kernel.org/project/netdevbpf/list/?series=810774
Major changes in v1:
====================
1. Implemented MVP queue API ndos to remove the userspace-visible
driver reset.
2. Fixed issues in the napi_pp_put_page() devmem frag unref path.
3. Removed RFC tag.
Many smaller addressed comments across all the patches (patches have
individual change log).
Full tree including the rest of the GVE driver changes:
https://github.com/mina/linux/commits/tcpdevmem-v1
Changes in RFC v3:
==================
1. Pulled in the memory-provider dependency from Jakub's RFC[1] to make the
series reviewable and mergeable.
2. Implemented multi-rx-queue binding which was a todo in v2.
3. Fix to cmsg handling.
The sticking point in RFC v2[2] was the device reset required to refill
the device rx-queues after the dmabuf bind/unbind. The solution
suggested as I understand is a subset of the per-queue management ops
Jakub suggested or similar:
https://lore.kernel.org/netdev/20230815171638.4c057dcd@kernel.org/
This is not addressed in this revision, because:
1. This point was discussed at netconf & netdev and there is openness to
using the current approach of requiring a device reset.
2. Implementing individual queue resetting seems to be difficult for my
test bed with GVE. My prototype to test this ran into issues with the
rx-queues not coming back up properly if reset individually. At the
moment I'm unsure if it's a mistake in the POC or a genuine issue in
the virtualization stack behind GVE, which currently doesn't test
individual rx-queue restart.
3. Our usecases are not bothered by requiring a device reset to refill
the buffer queues, and we'd like to support NICs that run into this
limitation with resetting individual queues.
My thought is that drivers that have trouble with per-queue configs can
use the support in this series, while drivers that support new netdev
ops to reset individual queues can automatically reset the queue as
part of the dma-buf bind/unbind.
The same approach with device resets is presented again for consideration
with other sticking points addressed.
This proposal includes the rx devmem path only proposed for merge. For a
snapshot of my entire tree which includes the GVE POC page pool support &
device memory support:
https://github.com/torvalds/linux/compare/master...mina:linux:tcpdevmem-v3
[1] https://lore.kernel.org/netdev/f8270765-a27b-6ccf-33ea-cda097168d79@redhat.…
[2] https://lore.kernel.org/netdev/CAHS8izOVJGJH5WF68OsRWFKJid1_huzzUK+hpKbLcL4…
Changes in RFC v2:
==================
The sticking point in RFC v1[1] was the dma-buf pages approach we used to
deliver the device memory to the TCP stack. RFC v2 is a proof-of-concept
that attempts to resolve this by implementing scatterlist support in the
networking stack, such that we can import the dma-buf scatterlist
directly. This is the approach proposed at a high level here[2].
Detailed changes:
1. Replaced dma-buf pages approach with importing scatterlist into the
page pool.
2. Replace the dma-buf pages centric API with a netlink API.
3. Removed the TX path implementation - there is no issue with
implementing the TX path with scatterlist approach, but leaving
out the TX path makes it easier to review.
4. Functionality is tested with this proposal, but I have not conducted
perf testing yet. I'm not sure there are regressions, but I removed
perf claims from the cover letter until they can be re-confirmed.
5. Added Signed-off-by: contributors to the implementation.
6. Fixed some bugs with the RX path since RFC v1.
Any feedback welcome, but specifically the biggest pending questions
needing feedback IMO are:
1. Feedback on the scatterlist-based approach in general.
2. Netlink API (Patch 1 & 2).
3. Approach to handle all the drivers that expect to receive pages from
the page pool (Patch 6).
[1] https://lore.kernel.org/netdev/dfe4bae7-13a0-3c5d-d671-f61b375cb0b4@gmail.c…
[2] https://lore.kernel.org/netdev/CAHS8izPm6XRS54LdCDZVd0C75tA1zHSu6jLVO8nzTLX…
==================
* TL;DR:
Device memory TCP (devmem TCP) is a proposal for transferring data to and/or
from device memory efficiently, without bouncing the data to a host memory
buffer.
* Problem:
A large amount of data transfers have device memory as the source and/or
destination. Accelerators drastically increased the volume of such transfers.
Some examples include:
- ML accelerators transferring large amounts of training data from storage into
GPU/TPU memory. In some cases ML training setup time can be as long as 50% of
TPU compute time, improving data transfer throughput & efficiency can help
improving GPU/TPU utilization.
- Distributed training, where ML accelerators, such as GPUs on different hosts,
exchange data among them.
- Distributed raw block storage applications transfer large amounts of data with
remote SSDs, much of this data does not require host processing.
Today, the majority of the Device-to-Device data transfers the network are
implemented as the following low level operations: Device-to-Host copy,
Host-to-Host network transfer, and Host-to-Device copy.
The implementation is suboptimal, especially for bulk data transfers, and can
put significant strains on system resources, such as host memory bandwidth,
PCIe bandwidth, etc. One important reason behind the current state is the
kernel’s lack of semantics to express device to network transfers.
* Proposal:
In this patch series we attempt to optimize this use case by implementing
socket APIs that enable the user to:
1. send device memory across the network directly, and
2. receive incoming network packets directly into device memory.
Packet _payloads_ go directly from the NIC to device memory for receive and from
device memory to NIC for transmit.
Packet _headers_ go to/from host memory and are processed by the TCP/IP stack
normally. The NIC _must_ support header split to achieve this.
Advantages:
- Alleviate host memory bandwidth pressure, compared to existing
network-transfer + device-copy semantics.
- Alleviate PCIe BW pressure, by limiting data transfer to the lowest level
of the PCIe tree, compared to traditional path which sends data through the
root complex.
* Patch overview:
** Part 1: netlink API
Gives user ability to bind dma-buf to an RX queue.
** Part 2: scatterlist support
Currently the standard for device memory sharing is DMABUF, which doesn't
generate struct pages. On the other hand, networking stack (skbs, drivers, and
page pool) operate on pages. We have 2 options:
1. Generate struct pages for dmabuf device memory, or,
2. Modify the networking stack to process scatterlist.
Approach #1 was attempted in RFC v1. RFC v2 implements approach #2.
** part 3: page pool support
We piggy back on page pool memory providers proposal:
https://github.com/kuba-moo/linux/tree/pp-providers
It allows the page pool to define a memory provider that provides the
page allocation and freeing. It helps abstract most of the device memory
TCP changes from the driver.
** part 4: support for unreadable skb frags
Page pool iovs are not accessible by the host; we implement changes
throughput the networking stack to correctly handle skbs with unreadable
frags.
** Part 5: recvmsg() APIs
We define user APIs for the user to send and receive device memory.
Not included with this series is the GVE devmem TCP support, just to
simplify the review. Code available here if desired:
https://github.com/mina/linux/tree/tcpdevmem
This series is built on top of net-next with Jakub's pp-providers changes
cherry-picked.
* NIC dependencies:
1. (strict) Devmem TCP require the NIC to support header split, i.e. the
capability to split incoming packets into a header + payload and to put
each into a separate buffer. Devmem TCP works by using device memory
for the packet payload, and host memory for the packet headers.
2. (optional) Devmem TCP works better with flow steering support & RSS support,
i.e. the NIC's ability to steer flows into certain rx queues. This allows the
sysadmin to enable devmem TCP on a subset of the rx queues, and steer
devmem TCP traffic onto these queues and non devmem TCP elsewhere.
The NIC I have access to with these properties is the GVE with DQO support
running in Google Cloud, but any NIC that supports these features would suffice.
I may be able to help reviewers bring up devmem TCP on their NICs.
* Testing:
The series includes a udmabuf kselftest that show a simple use case of
devmem TCP and validates the entire data path end to end without
a dependency on a specific dmabuf provider.
** Test Setup
Kernel: net-next with this series and memory provider API cherry-picked
locally.
Hardware: Google Cloud A3 VMs.
NIC: GVE with header split & RSS & flow steering support.
Cc: Pavel Begunkov <asml.silence(a)gmail.com>
Cc: David Wei <dw(a)davidwei.uk>
Cc: Jason Gunthorpe <jgg(a)ziepe.ca>
Cc: Yunsheng Lin <linyunsheng(a)huawei.com>
Cc: Shailend Chand <shailend(a)google.com>
Cc: Harshitha Ramamurthy <hramamurthy(a)google.com>
Cc: Shakeel Butt <shakeel.butt(a)linux.dev>
Cc: Jeroen de Borst <jeroendb(a)google.com>
Cc: Praveen Kaligineedi <pkaligineedi(a)google.com>
Mina Almasry (13):
netdev: add netdev_rx_queue_restart()
net: netdev netlink api to bind dma-buf to a net device
netdev: support binding dma-buf to netdevice
netdev: netdevice devmem allocator
page_pool: convert to use netmem
page_pool: devmem support
memory-provider: dmabuf devmem memory provider
net: support non paged skb frags
net: add support for skbs with unreadable frags
tcp: RX path for devmem TCP
net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags
net: add devmem TCP documentation
selftests: add ncdevmem, netcat for devmem TCP
Documentation/netlink/specs/netdev.yaml | 57 +++
Documentation/networking/devmem.rst | 258 +++++++++++
Documentation/networking/index.rst | 1 +
arch/alpha/include/uapi/asm/socket.h | 6 +
arch/mips/include/uapi/asm/socket.h | 6 +
arch/parisc/include/uapi/asm/socket.h | 6 +
arch/sparc/include/uapi/asm/socket.h | 6 +
include/linux/skbuff.h | 61 ++-
include/linux/skbuff_ref.h | 11 +-
include/linux/socket.h | 1 +
include/net/devmem.h | 124 ++++++
include/net/mp_dmabuf_devmem.h | 44 ++
include/net/netdev_rx_queue.h | 5 +
include/net/netmem.h | 208 ++++++++-
include/net/page_pool/helpers.h | 124 ++++--
include/net/page_pool/types.h | 22 +-
include/net/sock.h | 2 +
include/net/tcp.h | 5 +-
include/trace/events/page_pool.h | 30 +-
include/uapi/asm-generic/socket.h | 6 +
include/uapi/linux/netdev.h | 19 +
include/uapi/linux/uio.h | 17 +
net/bpf/test_run.c | 5 +-
net/core/Makefile | 3 +-
net/core/datagram.c | 6 +
net/core/dev.c | 6 +-
net/core/devmem.c | 376 ++++++++++++++++
net/core/gro.c | 3 +-
net/core/netdev-genl-gen.c | 23 +
net/core/netdev-genl-gen.h | 6 +
net/core/netdev-genl.c | 103 +++++
net/core/netdev_rx_queue.c | 74 ++++
net/core/page_pool.c | 362 +++++++++-------
net/core/skbuff.c | 83 +++-
net/core/sock.c | 61 +++
net/ipv4/esp4.c | 3 +-
net/ipv4/tcp.c | 261 +++++++++++-
net/ipv4/tcp_input.c | 13 +-
net/ipv4/tcp_ipv4.c | 16 +
net/ipv4/tcp_minisocks.c | 2 +
net/ipv4/tcp_output.c | 5 +-
net/ipv6/esp6.c | 3 +-
net/packet/af_packet.c | 4 +-
tools/include/uapi/linux/netdev.h | 19 +
tools/testing/selftests/net/.gitignore | 1 +
tools/testing/selftests/net/Makefile | 5 +
tools/testing/selftests/net/ncdevmem.c | 542 ++++++++++++++++++++++++
47 files changed, 2753 insertions(+), 251 deletions(-)
create mode 100644 Documentation/networking/devmem.rst
create mode 100644 include/net/devmem.h
create mode 100644 include/net/mp_dmabuf_devmem.h
create mode 100644 net/core/devmem.c
create mode 100644 net/core/netdev_rx_queue.c
create mode 100644 tools/testing/selftests/net/ncdevmem.c
--
2.45.2.741.gdbec12cfda-goog
Currently if we request a feature that is not set in the Kernel
config we fail silently and return all the available features. However,
the man page indicates we should return an EINVAL.
We need to fix this issue since we can end up with a Kernel warning
should a program request the feature UFFD_FEATURE_WP_UNPOPULATED on
a kernel with the config not set with this feature.
[ 200.812896] WARNING: CPU: 91 PID: 13634 at mm/memory.c:1660 zap_pte_range+0x43d/0x660
[ 200.820738] Modules linked in:
[ 200.869387] CPU: 91 PID: 13634 Comm: userfaultfd Kdump: loaded Not tainted 6.9.0-rc5+ #8
[ 200.877477] Hardware name: Dell Inc. PowerEdge R6525/0N7YGH, BIOS 2.7.3 03/30/2022
[ 200.885052] RIP: 0010:zap_pte_range+0x43d/0x660
Fixes: e06f1e1dd499 ("userfaultfd: wp: enabled write protection in userfaultfd API")
Signed-off-by: Audra Mitchell <audra(a)redhat.com>
---
fs/userfaultfd.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index eee7320ab0b0..17e409ceaa33 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -2057,7 +2057,7 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
goto out;
features = uffdio_api.features;
ret = -EINVAL;
- if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES))
+ if (uffdio_api.api != UFFD_API)
goto err_out;
ret = -EPERM;
if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE))
@@ -2081,6 +2081,11 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx,
uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED;
uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC;
#endif
+
+ ret = -EINVAL;
+ if (features & ~uffdio_api.features)
+ goto err_out;
+
uffdio_api.ioctls = UFFD_API_IOCTLS;
ret = -EFAULT;
if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
--
2.44.0
Correctable memory errors are very common on servers with large
amount of memory, and are corrected by ECC, but with two
pain points to users:
1. Correction usually happens on the fly and adds latency overhead
2. Not-fully-proved theory states excessive correctable memory
errors can develop into uncorrectable memory error.
Soft offline is kernel's additional solution for memory pages
having (excessive) corrected memory errors. Impacted page is migrated
to healthy page if it is in use, then the original page is discarded
for any future use.
The actual policy on whether (and when) to soft offline should be
maintained by userspace, especially in case of an 1G HugeTLB page.
Soft-offline dissolves the HugeTLB page, either in-use or free, into
chunks of 4K pages, reducing HugeTLB pool capacity by 1 hugepage.
If userspace has not acknowledged such behavior, it may be surprised
when later mmap hugepages MAP_FAILED due to lack of hugepages.
In case of a transparent hugepage, it will be split into 4K pages
as well; userspace will stop enjoying the transparent performance.
In addition, discarding the entire 1G HugeTLB page only because of
corrected memory errors sounds very costly and kernel better not
doing under the hood. But today there are at least 2 such cases:
1. GHES driver sees both GHES_SEV_CORRECTED and
CPER_SEC_ERROR_THRESHOLD_EXCEEDED after parsing CPER.
2. RAS Correctable Errors Collector counts correctable errors per
PFN and when the counter for a PFN reaches threshold
In both cases, userspace has no control of the soft offline performed
by kernel's memory failure recovery.
This patch series give userspace the control of softofflining any page:
kernel only soft offlines raw page / transparent hugepage / HugeTLB
hugepage if userspace has agreed to. The interface to userspace is a
new sysctl called enable_soft_offline under /proc/sys/vm. By default
enable_soft_line is 1 to preserve existing behavior in kernel.
Changelog
v4 => v5:
* incorportate feedbacks from Muhammad Usama Anjum
<usama.anjum(a)collabora.com>
* refactor selftest to use what available in kselftest.h.
* update a comment in soft_offline_page.
v3 => v4:
* incorporate feedbacks from Miaohe Lin <linmiaohe(a)huawei.com>,
Andrew Morton <akpm(a)linux-foundation.org>, and
Oscar Salvador <osalvador(a)suse.de>.
* insert a refactor commit to unify soft offline's logs to follow
"Soft offline: 0x${pfn}: ${message}" format.
* some rewords in document: fail => will not perform.
* v4 is still based on commit 83a7eefedc9b ("Linux 6.10-rc3"),
akpm/mm-stable.
v2 => v3:
* incorporate feedbacks from Miaohe Lin <linmiaohe(a)huawei.com>,
Lance Yang <ioworker0(a)gmail.com>, Oscar Salvador <osalvador(a)suse.de>,
and David Rientjes <rientjes(a)google.com>.
* release potential refcount if enable_soft_offline is 0.
* soft_offline_page() returns EOPNOTSUPP if enable_soft_offline is 0.
* refactor hugetlb-soft-offline.c, for example, introduce
test_soft_offline_common to reduce repeated code.
* rewrite enable_soft_offline's documentation, adds more details about
the cost of soft-offline for transparent and hugetlb hugepages, and
components that are impacted when enable_soft_offline becomes 0.
* fix typos in commit messages.
* v3 is still based on commit 83a7eefedc9b ("Linux 6.10-rc3").
v1 => v2:
* incorporate feedbacks from both Miaohe Lin <linmiaohe(a)huawei.com> and
Jane Chu <jane.chu(a)oracle.com>.
* make the switch to control all pages, instead of HugeTLB specific.
* change the API from
/sys/kernel/mm/hugepages/hugepages-${size}kB/softoffline_corrected_errors
to /proc/sys/vm/enable_soft_offline.
* minor update to test code.
* update documentation of the user control API.
* v2 is based on commit 83a7eefedc9b ("Linux 6.10-rc3").
Jiaqi Yan (4):
mm/memory-failure: refactor log format in soft offline code
mm/memory-failure: userspace controls soft-offlining pages
selftest/mm: test enable_soft_offline behaviors
docs: mm: add enable_soft_offline sysctl
Documentation/admin-guide/sysctl/vm.rst | 32 +++
mm/memory-failure.c | 38 ++-
tools/testing/selftests/mm/.gitignore | 1 +
tools/testing/selftests/mm/Makefile | 1 +
.../selftests/mm/hugetlb-soft-offline.c | 227 ++++++++++++++++++
tools/testing/selftests/mm/run_vmtests.sh | 4 +
6 files changed, 295 insertions(+), 8 deletions(-)
create mode 100644 tools/testing/selftests/mm/hugetlb-soft-offline.c
--
2.45.2.741.gdbec12cfda-goog
Centralizes the definition of _GNU_SOURCE into lib.mk and addresses all
resulting macro redefinition warnings.
These patches will need to be merged in one shot to avoid redefinition
warnings.
The initial attempt at this patch was abandoned because it affected
lines in many source files and caused a large amount of churn. However,
from earlier discussions, centralizing _GNU_SOURCE is still desireable.
This attempt limits the changes to 1 source file and 12 Makefiles.
v1: https://lore.kernel.org/linux-kselftest/20240430235057.1351993-1-edliaw@goo…
v2: https://lore.kernel.org/linux-kselftest/20240507214254.2787305-1-edliaw@goo…
- Add -D_GNU_SOURCE to KHDR_INCLUDES so that it is in a single
location.
- Remove #define _GNU_SOURCE from source code to resolve redefinition
warnings.
v3: https://lore.kernel.org/linux-kselftest/20240509200022.253089-1-edliaw@goog…
- Rebase onto linux-next 20240508.
- Split patches by directory.
- Add -D_GNU_SOURCE directly to CFLAGS in lib.mk.
- Delete additional _GNU_SOURCE definitions from source code in
linux-next.
- Delete additional -D_GNU_SOURCE flags from Makefiles.
v4: https://lore.kernel.org/linux-kselftest/20240510000842.410729-1-edliaw@goog…
- Rebase onto linux-next 20240509.
- Remove Fixes tag from patches that drop _GNU_SOURCE definition.
- Restore space between comment and includes for selftests/damon.
v5: https://lore.kernel.org/linux-kselftest/20240522005913.3540131-1-edliaw@goo…
- Rebase onto linux-next 20240521
- Drop initial patches that modify KHDR_INCLUDES.
- Incorporate Mark Brown's patch to replace static_assert with warning.
- Don't drop #define _GNU_SOURCE from nolibc and wireguard.
- Change Makefiles for x86 and vDSO to append to CFLAGS.
v6:
- Rewrite patch to use -D_GNU_SOURCE= form in lib.mk.
- Reduce the amount of churn significantly by allowing definition to
coexist with source code macro defines.
Edward Liaw (13):
selftests/mm: Define _GNU_SOURCE to an empty string
selftests: Add -D_GNU_SOURCE= to CFLAGS in lib.mk
selftests/net: Append to lib.mk CFLAGS in Makefile
selftests/exec: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/futex: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/intel_pstate: Drop redundant -D_GNU_SOURCE CFLAGS in
Makefile
selftests/iommu: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/kvm: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/proc: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/resctrl: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/ring-buffer: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/riscv: Drop redundant -D_GNU_SOURCE CFLAGS in Makefile
selftests/sgx: Append CFLAGS from lib.mk to HOST_CFLAGS
tools/testing/selftests/exec/Makefile | 1 -
tools/testing/selftests/futex/functional/Makefile | 2 +-
tools/testing/selftests/intel_pstate/Makefile | 2 +-
tools/testing/selftests/iommu/Makefile | 2 --
tools/testing/selftests/kvm/Makefile | 2 +-
tools/testing/selftests/lib.mk | 3 +++
tools/testing/selftests/mm/thuge-gen.c | 2 +-
tools/testing/selftests/net/Makefile | 2 +-
tools/testing/selftests/net/tcp_ao/Makefile | 2 +-
tools/testing/selftests/proc/Makefile | 1 -
tools/testing/selftests/resctrl/Makefile | 2 +-
tools/testing/selftests/ring-buffer/Makefile | 1 -
tools/testing/selftests/riscv/mm/Makefile | 2 +-
tools/testing/selftests/sgx/Makefile | 2 +-
14 files changed, 12 insertions(+), 14 deletions(-)
--
2.45.2.741.gdbec12cfda-goog
This series introduces the selftests/arm directory, which tests 32 and
64-bit kernel compatibility with 32-bit ELFs running on the Aarch platform.
The need for this bucket of tests is that 32 bit applications built on
legacy ARM architecture must not break on the new Aarch64 platforms and
the 64-bit kernel. The kernel must emulate the data structures, system
calls and the registers according to Aarch32, when running a 32-bit
process; this directory fills that testing requirement.
One may find similarity between this directory and selftests/arm64; it is
advisable to refer to that since a lot has been pulled from there itself.
The mm directory includes a test for checking 4GB limit of the virtual
address space of a process.
The signal directory contains two tests, following a common theme: mangle
with arm_cpsr, dumped by the kernel to user space while invoking the signal
handler; kernel must spot this illegal attempt and terminate the program by
SEGV.
The elf directory includes a test for checking the 32-bit status of the ELF.
The abi directory includes two ptrace tests, in the first, a 32-bit parent
debugs a 32-bit child, and in the second, a 64-bit parent debugs a 32-bit
child. The second test will be skipped when running on a 32-bit kernel.
Credits to Mark Brown for suggesting this work.
Testing:
The series has been tested on the Aarch64 kernel. For the Aarch32 kernel,
I used qemu-system-arm with machine 'vexpress-a15', along with a buildroot
rootfs; the individual statically built tests pass on that, but building
the entire test suite on that remains untested, due to my lack of
experience with qemu and rootfses.
Since I have done some changes in selftests/arm64, I have tested that
those tests do not break.
v2->v3:
- mm, elf: Split into multiple testcases
- Eliminate copying in signal/ using ifdeffery and pulling from selftests/arm64
- Delete config file, since it does not make sense for testing a 32-bit kernel
- Split ptrace in selftests/arm64, and pull some stuff from there
- Add abi tests containing ptrace and ptrace_64
- Fix build warnings in selftests/arm64 (can be applied independent of this series)
v1->v2:
- Formatting changes
- Add .gitignore files and config file
v1:
- https://lore.kernel.org/all/20240405084410.256788-1-dev.jain@arm.com/
Dev Jain (9):
selftests/arm: Add mm test
selftests/arm: Add elf test
selftests: arm, arm64: Use ifdeffery to pull signal infrastructure
selftests/arm: Add signal tests
selftests/arm64: Fix build warnings for ptrace
selftests/arm64: Split ptrace, use ifdeffery
selftests/arm: Add ptrace test
selftests/arm: Add ptrace_64 test
selftests: Add build infrastructure along with README
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/arm/Makefile | 56 ++++++++
tools/testing/selftests/arm/README | 32 +++++
tools/testing/selftests/arm/abi/.gitignore | 4 +
tools/testing/selftests/arm/abi/Makefile | 26 ++++
tools/testing/selftests/arm/abi/ptrace.c | 82 +++++++++++
tools/testing/selftests/arm/abi/ptrace.h | 57 ++++++++
tools/testing/selftests/arm/abi/ptrace_64.c | 91 ++++++++++++
.../selftests/arm/abi/trivial_32bit_program.c | 14 ++
tools/testing/selftests/arm/elf/.gitignore | 2 +
tools/testing/selftests/arm/elf/Makefile | 6 +
tools/testing/selftests/arm/elf/parse_elf.c | 77 ++++++++++
tools/testing/selftests/arm/mm/.gitignore | 2 +
tools/testing/selftests/arm/mm/Makefile | 6 +
tools/testing/selftests/arm/mm/compat_va.c | 89 ++++++++++++
tools/testing/selftests/arm/signal/.gitignore | 3 +
tools/testing/selftests/arm/signal/Makefile | 30 ++++
.../selftests/arm/signal/test_signals.c | 2 +
.../selftests/arm/signal/test_signals.h | 2 +
.../selftests/arm/signal/test_signals_utils.c | 2 +
.../selftests/arm/signal/test_signals_utils.h | 2 +
.../testcases/mangle_cpsr_invalid_aif_bits.c | 33 +++++
.../mangle_cpsr_invalid_compat_toggle.c | 29 ++++
tools/testing/selftests/arm64/abi/ptrace.c | 121 ++--------------
tools/testing/selftests/arm64/abi/ptrace.h | 135 ++++++++++++++++++
.../selftests/arm64/signal/test_signals.h | 12 ++
.../arm64/signal/test_signals_utils.c | 51 +++++--
.../arm64/signal/test_signals_utils.h | 3 +
28 files changed, 850 insertions(+), 120 deletions(-)
create mode 100644 tools/testing/selftests/arm/Makefile
create mode 100644 tools/testing/selftests/arm/README
create mode 100644 tools/testing/selftests/arm/abi/.gitignore
create mode 100644 tools/testing/selftests/arm/abi/Makefile
create mode 100644 tools/testing/selftests/arm/abi/ptrace.c
create mode 100644 tools/testing/selftests/arm/abi/ptrace.h
create mode 100644 tools/testing/selftests/arm/abi/ptrace_64.c
create mode 100644 tools/testing/selftests/arm/abi/trivial_32bit_program.c
create mode 100644 tools/testing/selftests/arm/elf/.gitignore
create mode 100644 tools/testing/selftests/arm/elf/Makefile
create mode 100644 tools/testing/selftests/arm/elf/parse_elf.c
create mode 100644 tools/testing/selftests/arm/mm/.gitignore
create mode 100644 tools/testing/selftests/arm/mm/Makefile
create mode 100644 tools/testing/selftests/arm/mm/compat_va.c
create mode 100644 tools/testing/selftests/arm/signal/.gitignore
create mode 100644 tools/testing/selftests/arm/signal/Makefile
create mode 100644 tools/testing/selftests/arm/signal/test_signals.c
create mode 100644 tools/testing/selftests/arm/signal/test_signals.h
create mode 100644 tools/testing/selftests/arm/signal/test_signals_utils.c
create mode 100644 tools/testing/selftests/arm/signal/test_signals_utils.h
create mode 100644 tools/testing/selftests/arm/signal/testcases/mangle_cpsr_invalid_aif_bits.c
create mode 100644 tools/testing/selftests/arm/signal/testcases/mangle_cpsr_invalid_compat_toggle.c
create mode 100644 tools/testing/selftests/arm64/abi/ptrace.h
--
2.39.2
This patch series fix a minor issue in a program for DAMON selftest, and
implement new functionality selftests for DAMOS tried regions and
{min,max}_nr_regions. The test for max_nr_regions also test the
recovery from online tuning-caused limit violation, which was fixed by a
previous patch [1] titled "mm/damon/core: merge regions aggressively
when max_nr_regions is unmet".
The first patch fixes a minor problem in the articial memory access
pattern generator for tests. Following 3 patches (2-4) implement
schemes tried regions test. Then a couple of patches (5-6) implementing
static setup based {min,max}_nr_regions functionality test follows.
Final two patches (7-8) implement dynamic max_nr_regions update test.
[1] https://lore.kernel.org/20240624210650.53960C2BBFC@smtp.kernel.org
SeongJae Park (8):
selftests/damon/access_memory: use user-defined region size
selftests/damon/_damon_sysfs: support schemes_update_tried_regions
selftests/damon: implement a program for even-numbered memory regions
access
selftests/damon: implement DAMOS tried regions test
selftests/damon/_damon_sysfs: implement kdamonds stop function
selftests/damon: implement test for min/max_nr_regions
_damon_sysfs: implement commit() for online parameters update
selftests/damon/damon_nr_regions: test online-tuned max_nr_regions
tools/testing/selftests/damon/Makefile | 3 +-
tools/testing/selftests/damon/_damon_sysfs.py | 65 +++++++-
tools/testing/selftests/damon/access_memory.c | 2 +-
.../selftests/damon/access_memory_even.c | 42 +++++
.../selftests/damon/damon_nr_regions.py | 145 ++++++++++++++++++
.../selftests/damon/damos_tried_regions.py | 65 ++++++++
6 files changed, 319 insertions(+), 3 deletions(-)
create mode 100644 tools/testing/selftests/damon/access_memory_even.c
create mode 100644 tools/testing/selftests/damon/damon_nr_regions.py
create mode 100644 tools/testing/selftests/damon/damos_tried_regions.py
base-commit: 99348045d11f3bac71146b381f90b0aa39855ee7
--
2.39.2
Currently, if a user wants to run pmtu.sh and cover all the provided test
cases, they need to install the Open vSwitch userspace utilities. This
dependency is difficult for users as well as CI environments, because the
userspace build and setup may require lots of support and devel packages
to be installed, system setup to be correct, and things like permissions
and selinux policies to be properly configured.
The kernel selftest suite includes an ovs-dpctl.py utility which can
interact with the openvswitch module directly. This lets developers and
CI environments run without needing too many extra dependencies - just
the pyroute2 python package.
This series enhances the ovs-dpctl utility to provide support for set()
and tunnel() flow specifiers, better ipv6 handling support, and the
ability to add tunnel vports, and LWT interfaces. Finally, it modifies
the pmtu.sh script to call the ovs-dpctl.py utility rather than the
typical OVS userspace utilities.
Aaron Conole (7):
selftests: openvswitch: Support explicit tunnel port creation.
selftests: openvswitch: Refactor actions parsing.
selftests: openvswitch: Add set() and set_masked() support.
selftests: openvswitch: Add support for tunnel() key.
selftests: openvswitch: Support implicit ipv6 arguments.
selftests: net: Use the provided dpctl rather than the vswitchd for
tests.
selftests: net: add config for openvswitch
tools/testing/selftests/net/config | 5 +
.../selftests/net/openvswitch/ovs-dpctl.py | 366 +++++++++++++++---
tools/testing/selftests/net/pmtu.sh | 145 +++++--
3 files changed, 450 insertions(+), 66 deletions(-)
--
2.45.1