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://lkml.kernel.org/r/9dfd717d-857d-493d-a606-b635d72ba...@amacapital.net
[2]: https://lkml.kernel.org/r/749919a4-cdb1-48a3-adb4-adb81a5fa...@intel.com
Fixes: f77084d96355 ("x86/mm/pat: Disable preemption around __flush_tlb_all()")
Cc: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Borislav Petkov <b...@alien8.de>
Cc: <sta...@vger.kernel.org>
Reported-by: Andy Lutomirski <l...@kernel.org>
Suggested-by: Dave Hansen <dave.han...@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
arch/x86/mm/init_64.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 3e25ac2793ef..484c1b92f078 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -584,7 +584,6 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr,
unsigned long paddr_end,
paddr_end,
page_size_mask,
prot);
- __flush_tlb_all();
continue;
}
/*
@@ -627,7 +626,6 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr,
unsigned long paddr_end,
pud_populate_safe(&init_mm, pud, pmd);
spin_unlock(&init_mm.page_table_lock);
}
- __flush_tlb_all();
update_page_count(PG_LEVEL_1G, pages);
@@ -668,7 +666,6 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr,
unsigned long paddr_end,
paddr_last = phys_pud_init(pud, paddr,
paddr_end,
page_size_mask);
- __flush_tlb_all();
continue;
}
@@ -680,7 +677,6 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr,
unsigned long paddr_end,
p4d_populate_safe(&init_mm, p4d, pud);
spin_unlock(&init_mm.page_table_lock);
}
- __flush_tlb_all();
return paddr_last;
}
@@ -733,8 +729,6 @@ kernel_physical_mapping_init(unsigned long paddr_start,
if (pgd_changed)
sync_global_pgds(vaddr_start, vaddr_end - 1);
- __flush_tlb_all();
-
return paddr_last;
}
