During the integration of the RTL8239 POE chip + its frontend MCU, it was
noticed that multi-byte operations were basically broken in the current
driver.
Tests using SMBus Block Writes showed that the data (after the Wr maker +
Ack) was mixed up on the wire. At first glance, it looked like an
endianness problem. But for transfers where the number of count + data
bytes was not divisible by 4, the last bytes were not looking like an
endianness problem because they were in the wrong order but not for example
0 - which would be the case for an endianness problem with 32 bit
registers. At the end, it turned out to be the way how i2c_write tried to
add the bytes to the send registers.
Each 32 bit register was used similar to a shift register - shifting the
various bytes up the register while the next one is added to the least
significant byte. But the I2C controller expects the first byte of the
transmission in the least significant byte of the first register. And the
last byte (assuming it is a 16 byte transfer) is expected in the most
significant byte of the fourth register.
While doing these tests, it was also observed that the count byte was
missing from the SMBus Block Writes. The driver just removed them from the
data->block (from the I2C subsystem). But the I2C controller DOES NOT
automatically add this byte - for example by using the configured
transmission length.
The RTL8239 MCU is not actually an SMBus compliant device. Instead, it
expects I2C Block Reads + I2C Block Writes. But according to the already
identified bugs in the driver, it was clear that the I2C controller can
simply be modified to not send the count byte for I2C_SMBUS_I2C_BLOCK_DATA.
The receive part just needs to write the content of the receive buffer to
the correct position in data->block.
While the on-wire format was now correct, reads were still not possible
against the MCU (for the RTL8239 POE chip). It was always timing out
because the 2ms were not enough for sending the read request and then
receiving the 12 byte answer.
These changes were originally submitted to OpenWrt. But there are plans to
migrate OpenWrt to the upstream Linux driver. As a result, the pull request
was stopped and the changes were redone against this driver.
For reasons of transparency: The work on I2C_SMBUS_I2C_BLOCK_DATA support
for the RTL8239-MCU was done on RTL931xx. All problems were therefore
detected with the patches from Jonas Jelonek [1] and not the vanilla Linux
driver. But looking through the code, it seems like these are NOT
regressions introduced by the RTL931x patchset.
I've picked up Alex Guo's patch [2] to reduce conflicts between pending
fixes.
[1] https://patchwork.ozlabs.org/project/linux-i2c/cover/20250727114800.3046-1-…
[2] https://lore.kernel.org/r/20250615235248.529019-1-alexguo1023@gmail.com
Signed-off-by: Sven Eckelmann <sven(a)narfation.org>
---
Changes in v4:
- Provide only "write" examples for "i2c: rtl9300: Fix multi-byte I2C write"
- drop the second initialization of vals in rtl9300_i2c_write() directly in
the "Fix multi-byte I2C write" fix
- indicate in target branch for each patch in PATCH prefix
- minor commit message cleanups
- Link to v3: https://lore.kernel.org/r/20250804-i2c-rtl9300-multi-byte-v3-0-e20607e1b28c…
Changes in v3:
- integrated patch
https://lore.kernel.org/r/20250615235248.529019-1-alexguo1023@gmail.com
to avoid conflicts in the I2C_SMBUS_BLOCK_DATA code
- added Fixes and stable(a)vger.kernel.org to Alex Guo's patch
- added Chris Packham's Reviewed-by/Acked-by
- Link to v2: https://lore.kernel.org/r/20250803-i2c-rtl9300-multi-byte-v2-0-9b7b759fe2b6…
Changes in v2:
- add the missing transfer width and read length increase for the SMBus
Write/Read
- Link to v1: https://lore.kernel.org/r/20250802-i2c-rtl9300-multi-byte-v1-0-5f687e0098e2…
---
Alex Guo (1):
[i2c-host-fixes] i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer
Harshal Gohel (2):
[i2c-host-fixes] i2c: rtl9300: Fix multi-byte I2C write
[i2c-host] i2c: rtl9300: Implement I2C block read and write
Sven Eckelmann (2):
[i2c-host-fixes] i2c: rtl9300: Increase timeout for transfer polling
[i2c-host-fixes] i2c: rtl9300: Add missing count byte for SMBus Block Ops
drivers/i2c/busses/i2c-rtl9300.c | 50 +++++++++++++++++++++++++++++++++-------
1 file changed, 42 insertions(+), 8 deletions(-)
---
base-commit: 09eaa2a604ed1bfda7e6fb10488127ce8fdc8048
change-id: 20250802-i2c-rtl9300-multi-byte-edaa1fb0872c
Best regards,
--
Sven Eckelmann <sven(a)narfation.org>
The patch titled
Subject: kho: warn if KHO is disabled due to an error
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
kho-warn-if-kho-is-disabled-due-to-an-error.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Subject: kho: warn if KHO is disabled due to an error
Date: Fri, 8 Aug 2025 20:18:04 +0000
During boot scratch area is allocated based on command line parameters or
auto calculated. However, scratch area may fail to allocate, and in that
case KHO is disabled. Currently, no warning is printed that KHO is
disabled, which makes it confusing for the end user to figure out why KHO
is not available. Add the missing warning message.
Link: https://lkml.kernel.org/r/20250808201804.772010-4-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org>
Acked-by: Pratyush Yadav <pratyush(a)kernel.org>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Arnd Bergmann <arnd(a)arndb.de>
Cc: Baoquan He <bhe(a)redhat.com>
Cc: Changyuan Lyu <changyuanl(a)google.com>
Cc: Coiby Xu <coxu(a)redhat.com>
Cc: Dave Vasilevsky <dave(a)vasilevsky.ca>
Cc: Eric Biggers <ebiggers(a)google.com>
Cc: Kees Cook <kees(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
kernel/kexec_handover.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/kexec_handover.c~kho-warn-if-kho-is-disabled-due-to-an-error
+++ a/kernel/kexec_handover.c
@@ -564,6 +564,7 @@ err_free_scratch_areas:
err_free_scratch_desc:
memblock_free(kho_scratch, kho_scratch_cnt * sizeof(*kho_scratch));
err_disable_kho:
+ pr_warn("Failed to reserve scratch area, disabling kexec handover\n");
kho_enable = false;
}
_
Patches currently in -mm which might be from pasha.tatashin(a)soleen.com are
kho-init-new_physxa-phys_bits-to-fix-lockdep.patch
kho-mm-dont-allow-deferred-struct-page-with-kho.patch
kho-warn-if-kho-is-disabled-due-to-an-error.patch
The patch titled
Subject: kho: mm: don't allow deferred struct page with KHO
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
kho-mm-dont-allow-deferred-struct-page-with-kho.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Subject: kho: mm: don't allow deferred struct page with KHO
Date: Fri, 8 Aug 2025 20:18:03 +0000
KHO uses struct pages for the preserved memory early in boot, however,
with deferred struct page initialization, only a small portion of memory
has properly initialized struct pages.
This problem was detected where vmemmap is poisoned, and illegal flag
combinations are detected.
Don't allow them to be enabled together, and later we will have to teach
KHO to work properly with deferred struct page init kernel feature.
Link: https://lkml.kernel.org/r/20250808201804.772010-3-pasha.tatashin@soleen.com
Fixes: 990a950fe8fd ("kexec: add config option for KHO")
Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org>
Acked-by: Pratyush Yadav <pratyush(a)kernel.org>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Arnd Bergmann <arnd(a)arndb.de>
Cc: Baoquan He <bhe(a)redhat.com>
Cc: Changyuan Lyu <changyuanl(a)google.com>
Cc: Coiby Xu <coxu(a)redhat.com>
Cc: Dave Vasilevsky <dave(a)vasilevsky.ca>
Cc: Eric Biggers <ebiggers(a)google.com>
Cc: Kees Cook <kees(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
kernel/Kconfig.kexec | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/Kconfig.kexec~kho-mm-dont-allow-deferred-struct-page-with-kho
+++ a/kernel/Kconfig.kexec
@@ -97,6 +97,7 @@ config KEXEC_JUMP
config KEXEC_HANDOVER
bool "kexec handover"
depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE
+ depends on !DEFERRED_STRUCT_PAGE_INIT
select MEMBLOCK_KHO_SCRATCH
select KEXEC_FILE
select DEBUG_FS
_
Patches currently in -mm which might be from pasha.tatashin(a)soleen.com are
kho-init-new_physxa-phys_bits-to-fix-lockdep.patch
kho-mm-dont-allow-deferred-struct-page-with-kho.patch
kho-warn-if-kho-is-disabled-due-to-an-error.patch
The patch titled
Subject: kho: init new_physxa->phys_bits to fix lockdep
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
kho-init-new_physxa-phys_bits-to-fix-lockdep.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Subject: kho: init new_physxa->phys_bits to fix lockdep
Date: Fri, 8 Aug 2025 20:18:02 +0000
Patch series "Several KHO Hotfixes".
Three unrelated fixes for Kexec Handover.
This patch (of 3):
Lockdep shows the following warning:
INFO: trying to register non-static key. The code is fine but needs
lockdep annotation, or maybe you didn't initialize this object before use?
turning off the locking correctness validator.
[<ffffffff810133a6>] dump_stack_lvl+0x66/0xa0
[<ffffffff8136012c>] assign_lock_key+0x10c/0x120
[<ffffffff81358bb4>] register_lock_class+0xf4/0x2f0
[<ffffffff813597ff>] __lock_acquire+0x7f/0x2c40
[<ffffffff81360cb0>] ? __pfx_hlock_conflict+0x10/0x10
[<ffffffff811707be>] ? native_flush_tlb_global+0x8e/0xa0
[<ffffffff8117096e>] ? __flush_tlb_all+0x4e/0xa0
[<ffffffff81172fc2>] ? __kernel_map_pages+0x112/0x140
[<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
[<ffffffff81359556>] lock_acquire+0xe6/0x280
[<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
[<ffffffff8100b9e0>] _raw_spin_lock+0x30/0x40
[<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
[<ffffffff813ec327>] xa_load_or_alloc+0x67/0xe0
[<ffffffff813eb4c0>] kho_preserve_folio+0x90/0x100
[<ffffffff813ebb7f>] __kho_finalize+0xcf/0x400
[<ffffffff813ebef4>] kho_finalize+0x34/0x70
This is becase xa has its own lock, that is not initialized in
xa_load_or_alloc.
Modifiy __kho_preserve_order(), to properly call
xa_init(&new_physxa->phys_bits);
Link: https://lkml.kernel.org/r/20250808201804.772010-2-pasha.tatashin@soleen.com
Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org>
Cc: Alexander Graf <graf(a)amazon.com>
Cc: Arnd Bergmann <arnd(a)arndb.de>
Cc: Baoquan He <bhe(a)redhat.com>
Cc: Changyuan Lyu <changyuanl(a)google.com>
Cc: Coiby Xu <coxu(a)redhat.com>
Cc: Dave Vasilevsky <dave(a)vasilevsky.ca>
Cc: Eric Biggers <ebiggers(a)google.com>
Cc: Kees Cook <kees(a)kernel.org>
Cc: Pratyush Yadav <pratyush(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
kernel/kexec_handover.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
--- a/kernel/kexec_handover.c~kho-init-new_physxa-phys_bits-to-fix-lockdep
+++ a/kernel/kexec_handover.c
@@ -144,14 +144,34 @@ static int __kho_preserve_order(struct k
unsigned int order)
{
struct kho_mem_phys_bits *bits;
- struct kho_mem_phys *physxa;
+ struct kho_mem_phys *physxa, *new_physxa;
const unsigned long pfn_high = pfn >> order;
might_sleep();
- physxa = xa_load_or_alloc(&track->orders, order, sizeof(*physxa));
- if (IS_ERR(physxa))
- return PTR_ERR(physxa);
+ physxa = xa_load(&track->orders, order);
+ if (!physxa) {
+ int err;
+
+ new_physxa = kzalloc(sizeof(*physxa), GFP_KERNEL);
+ if (!new_physxa)
+ return -ENOMEM;
+
+ xa_init(&new_physxa->phys_bits);
+ physxa = xa_cmpxchg(&track->orders, order, NULL, new_physxa,
+ GFP_KERNEL);
+
+ err = xa_err(physxa);
+ if (err || physxa) {
+ xa_destroy(&new_physxa->phys_bits);
+ kfree(new_physxa);
+
+ if (err)
+ return err;
+ } else {
+ physxa = new_physxa;
+ }
+ }
bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS,
sizeof(*bits));
_
Patches currently in -mm which might be from pasha.tatashin(a)soleen.com are
kho-init-new_physxa-phys_bits-to-fix-lockdep.patch
kho-mm-dont-allow-deferred-struct-page-with-kho.patch
kho-warn-if-kho-is-disabled-due-to-an-error.patch
On Sat, 9 Aug 2025 04:55:18 +0900 Sang-Heon Jeon <ekffu200098(a)gmail.com> wrote:
> damos_commit_ops_filters() incorrectly uses damos_nth_filter() which
> iterates core_filters. As a result, performing a commit unintentionally
> corrupts ops_filters.
>
> Add damos_nth_ops_filter() which iterates ops_filters. Use this function
> to fix issues caused by wrong iteration.
Thank you for finding and fixing this bug! Since this bug is better to be
fixed as soon as possible, could you please send the next version of this patch
as an individual one, rather than as a part of this patchset?
>
> Signed-off-by: Sang-Heon Jeon <ekffu200098(a)gmail.com>
Let's add below for stable kernel maintainers[1].
Fixes: 3607cc590f18 ("mm/damon/core: support committing ops_filters") # 6.15.x
Cc: stable(a)vger.kernel.org
And the fix looks good to me, so
Reviewed-by: SeongJae Park <sj(a)kernel.org>
[...]
[1] https://docs.kernel.org/process/stable-kernel-rules.html
Thanks,
SJ