On Fri, Nov 30, 2018 at 04:35:32PM -0800, Dan Williams wrote:
Commit f77084d96355 "x86/mm/pat: Disable preemption around __flush_tlb_all()" addressed a case where __flush_tlb_all() is called without preemption being disabled. It also left a warning to catch other cases where preemption is not disabled. That warning triggers for the memory hotplug path which is also used for persistent memory enabling:
WARNING: CPU: 35 PID: 911 at ./arch/x86/include/asm/tlbflush.h:460 RIP: 0010:__flush_tlb_all+0x1b/0x3a [..] Call Trace: phys_pud_init+0x29c/0x2bb kernel_physical_mapping_init+0xfc/0x219 init_memory_mapping+0x1a5/0x3b0 arch_add_memory+0x2c/0x50 devm_memremap_pages+0x3aa/0x610 pmem_attach_disk+0x585/0x700 [nd_pmem]
Andy wondered why a path that can sleep was using __flush_tlb_all() [1] and Dave confirmed the expectation for TLB flush is for modifying / invalidating existing pte entries, but not initial population [2]. Drop the usage of __flush_tlb_all() in phys_{p4d,pud,pmd}_init() on the expectation that this path is only ever populating empty entries for the linear map. Note, at linear map teardown time there is a call to the all-cpu flush_tlb_all() to invalidate the removed mappings.
Fixes: f77084d96355 ("x86/mm/pat: Disable preemption around __flush_tlb_all()") Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Thomas Gleixner tglx@linutronix.de Cc: Peter Zijlstra peterz@infradead.org Cc: Borislav Petkov bp@alien8.de Cc: stable@vger.kernel.org Reported-by: Andy Lutomirski luto@kernel.org Suggested-by: Dave Hansen dave.hansen@linux.intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com
Hi Dan,
This patch on it's own doesn't apply to any of the stable trees, does it maybe depend on some of the previous patches in this series?
-- Thanks, Sasha