6.12-stable review patch. If anyone has any objections, please let me know.
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From: James Morse james.morse@arm.com
[ Upstream commit a121798ae669351ec0697c94f71c3a692b2a755b ]
Commit
6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid")
added logic that causes resctrl to search for the CLOSID with the fewest dirty cache lines when creating a new control group, if requested by the arch code. This depends on the values read from the llc_occupancy counters. The logic is applicable to architectures where the CLOSID effectively forms part of the monitoring identifier and so do not allow complete freedom to choose an unused monitoring identifier for a given CLOSID.
This support missed that some platforms may not have these counters. This causes a NULL pointer dereference when creating a new control group as the array was not allocated by dom_data_init().
As this feature isn't necessary on platforms that don't have cache occupancy monitors, add this to the check that occurs when a new control group is allocated.
Fixes: 6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid") Signed-off-by: James Morse james.morse@arm.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Shaopeng Tan tan.shaopeng@jp.fujitsu.com Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Reinette Chatre reinette.chatre@intel.com Reviewed-by: Tony Luck tony.luck@intel.com Reviewed-by: Fenghua Yu fenghuay@nvidia.com Reviewed-by: Babu Moger babu.moger@amd.com Tested-by: Carl Worth carl@os.amperecomputing.com # arm64 Tested-by: Shaopeng Tan tan.shaopeng@jp.fujitsu.com Tested-by: Peter Newman peternewman@google.com Tested-by: Amit Singh Tomar amitsinght@marvell.com # arm64 Tested-by: Shanker Donthineni sdonthineni@nvidia.com # arm64 Tested-by: Babu Moger babu.moger@amd.com Link: https://lore.kernel.org/r/20250311183715.16445-2-james.morse@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index d7163b764c626..2d48db66fca85 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -148,7 +148,8 @@ static int closid_alloc(void)
lockdep_assert_held(&rdtgroup_mutex);
- if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) { + if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID) && + is_llc_occupancy_enabled()) { cleanest_closid = resctrl_find_cleanest_closid(); if (cleanest_closid < 0) return cleanest_closid;