Messages in this thread | | | Date | Sun, 2 Dec 2018 01:43:04 -0500 | From | Sasha Levin <> | Subject | Re: [PATCH v2 5/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init() |
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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. > >[1]: https://lore.kernel.org/lkml/9DFD717D-857D-493D-A606-B635D72BAC21@amacapital.net >[2]: https://lore.kernel.org/lkml/749919a4-cdb1-48a3-adb4-adb81a5fa0b5@intel.com > >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
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