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charset=us-ascii Content-Disposition: inline In-Reply-To: <20260529075712.1181039-1-sshegde@linux.ibm.com> On Fri, May 29, 2026 at 01:27:12PM +0530, Shrikanth Hegde wrote: > Venkat Reported a boot kernel panic next-20260522. Git bisect pointed to > b5ea300a17e3 ("sched/cache: Make LLC id continuous") > > Stacktrace points to llc_mask being null. > > NIP [c000000000e58504] _find_first_bit+0x44/0x130 > LR [c000000000e58500] _find_first_bit+0x40/0x130 > Call Trace: > build_sched_domains+0xad8/0xe50 > sched_init_smp+0xa8/0x164 > kernel_init_freeable+0x250/0x370 > ret_from_kernel_user_thread+0x14/0x1c > > On powerpc, cpu_coregroup_mask is available only when the underlying > hardware support coregroup. In shared LPAR, QEMU guest or power9 etc > coregroup isn't supported. In such cases llc_mask was being referenced > when it was null leading to panic. > > On powerpc, LLC is at SMT core level. So assumption that coregroup(MC) > domain point to LLC is wrong. Provide a way for archs to say where its > LLC is if it not at MC domain. > > Based on tip/master at 5c89783224e9 ("Merge branch into tip/master: 'x86/tdx'") > Cc: stable@vger.kernel.org This seems unwarranted, the patch breaking stuff is in tip:sched/core. > Fixes: b5ea300a17e3 ("sched/cache: Make LLC id continuous") > Reported-by: Venkat Rao Bagalkote > Closes: https://lore.kernel.org/all/51154de7-3700-4cb4-82f2-1b3a8fa427f7@linux.ibm.com/ > Reviewed-by: Chen Yu > Tested-by: Venkat Rao Bagalkote > Tested-by: Ritesh Harjani (IBM) > Co-developed-by: Chen, Yu C > Signed-off-by: Shrikanth Hegde Thanks all! I'll stick this in tip:sched/core to go along with the patches that broke stuff.