Re: PowerPC: Random memory corruption causing kernel oops on Power11

[Venkat Rao Bagalkote <venkat88@linux.ibm.com>]

On 29/05/26 12:20 pm, Venkat Rao Bagalkote wrote:
> Greetings!!!
>
> Kernel 7.1.0-rc5-next-20260528 crashes randomly on IBM Power11 
> hardware. Attached is the config file.
>
> **System:**
> - Hardware: IBM 9080-HEX Power11, pSeries
> - Broken: 7.1.0-rc5-next-20260528
> - Config: 64K pages, Radix MMU
>
>
> **Problem:**
> Different crash at each reboot.
>
>
> **Example Crash 1:**
>
> [    4.678016] BUG: Unable to handle kernel data access at 
> 0xbffffffefec10628
> [    4.678112] NIP [c008000004e3c74c] 
> xfs_dir2_block_lookup_int+0xd4/0x300 [xfs]
> [    4.678281] [c000000005eaf7d0] [c008000004e3c6d4] 
> xfs_dir2_block_lookup_int+0x5c/0x300 [xfs]
> [    4.678363] [c000000005eaf850] [c008000004e3d56c] 
> xfs_dir2_block_lookup+0x44/0x1e0 [xfs]
>
>
> **Example Crash 2:**
>
> [    6.327116] BUG: Unable to handle kernel data access at 
> 0x762f736563697695
> [    6.327242] NIP [c00000000073cf34] __refill_obj_stock+0x74/0x2c0
> [    6.327261] [c0000013ffdbfd10] [c0000000007418b8] 
> obj_cgroup_uncharge+0x48/0x70
> [    6.327271] [c0000013ffdbfd50] [c00000000062fffc] 
> free_percpu.part.0+0x12c/0x630
>
>

Git bisect is pointing to 54067bacb49c selinux: hooks: use __getname() 
to allocate path buffer as the first bad commit.


# git bisect good
54067bacb49caeada82b20b6bd706dca0cb99ffc is the first bad commit
commit 54067bacb49caeada82b20b6bd706dca0cb99ffc
Author: Mike Rapoport (Microsoft) <rppt@kernel.org>
Date:   Wed May 20 11:18:56 2026 +0300

     selinux: hooks: use __getname() to allocate path buffer

     selinux_genfs_get_sid() allocates memory for a path with 
__get_free_page()
     although there is a dedicated helper for allocation of file paths:
     __getname().

     Replace __get_free_page() for allocation of a path buffer with 
__getname().

     Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
     Signed-off-by: Paul Moore <paul@paul-moore.com>

  security/selinux/hooks.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

# git bisect log
git bisect start
# status: waiting for both good and bad commits
# good: [e7ae89a0c97ce2b68b0983cd01eda67cf373517d] Linux 7.1-rc5
git bisect good e7ae89a0c97ce2b68b0983cd01eda67cf373517d
# status: waiting for bad commit, 1 good commit known
# bad: [f7af91adc230aa99e23330ecf85bc9badd9780ad] Add linux-next 
specific files for 20260528
git bisect bad f7af91adc230aa99e23330ecf85bc9badd9780ad
# good: [7189ebc81d5e4cb4e03dc4040b07c582b95b09d5] Merge branch 
'nand/next' of https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git
git bisect good 7189ebc81d5e4cb4e03dc4040b07c582b95b09d5
# skip: [d22aa6f023f3fc275e1f994045a6b347288b2e5a] Merge branch 
'watchdog-next' of 
https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git
git bisect skip d22aa6f023f3fc275e1f994045a6b347288b2e5a
# good: [40d5349aaaae55ec62451bfacc6189cf44ce02cb] iio: adc: ti-ads1298: 
Add parentheses around macro parameter
git bisect good 40d5349aaaae55ec62451bfacc6189cf44ce02cb
# good: [6665ab5cf8e74edba571d3d2f31e575f89373dfd] Merge branch 
'next-integrity' of 
https://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
git bisect good 6665ab5cf8e74edba571d3d2f31e575f89373dfd
# bad: [4cc60db652df7ae5d659ec23325c341a52d065e0] Merge branch 
'driver-core-next' of 
https://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core.git
git bisect bad 4cc60db652df7ae5d659ec23325c341a52d065e0
# bad: [e1d469c38defe7fcb8c6f62a2b7dbf4a103da300] Merge branch 'master' 
of https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
git bisect bad e1d469c38defe7fcb8c6f62a2b7dbf4a103da300
# good: [4678d11f294de0fd295a265e02955b5d1a4a2684] Merge branch into 
tip/master: 'x86/tdx'
git bisect good 4678d11f294de0fd295a265e02955b5d1a4a2684
# bad: [9397e02d718fc52703d753f489042293cd807dd3] Merge branch 'next' of 
https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git
git bisect bad 9397e02d718fc52703d753f489042293cd807dd3
# good: [c574bdb524095d24169e229b2e3b9318c72e733a] watchdog: 
ziirave_wdt: Use named initializers for struct i2c_device_id
git bisect good c574bdb524095d24169e229b2e3b9318c72e733a
# bad: [5568ff6b5e30c7736c24e2096e968c8785c2c245] Merge branch 
'for-next-tpm' of 
https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git
git bisect bad 5568ff6b5e30c7736c24e2096e968c8785c2c245
# bad: [23f6b2756d28e76464c7e87850d3d4f6d8c8b365] Merge branch 'next' of 
https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux.git
git bisect bad 23f6b2756d28e76464c7e87850d3d4f6d8c8b365
# good: [ecf41f6218b58c72f1511e395e480f70a9f44889] selinux: reorder 
policydb_index()
git bisect good ecf41f6218b58c72f1511e395e480f70a9f44889
# bad: [54067bacb49caeada82b20b6bd706dca0cb99ffc] selinux: hooks: use 
__getname() to allocate path buffer
git bisect bad 54067bacb49caeada82b20b6bd706dca0cb99ffc
# good: [2f0af91353cb64b54cfee5423820d2149039338d] selinux: check for 
simple types
git bisect good 2f0af91353cb64b54cfee5423820d2149039338d
# good: [bc3f08d1ef15ebbd32faf0b10cd9699b90b9d30c] selinux: use 
k[mz]alloc() to allocate temporary buffers
git bisect good bc3f08d1ef15ebbd32faf0b10cd9699b90b9d30c
# first bad commit: [54067bacb49caeada82b20b6bd706dca0cb99ffc] selinux: 
hooks: use __getname() to allocate path buffer


> If you happen to fix this, please add below tag.
>
> Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
>
>
> Regards,
>
> Venkat.
>