* [PATCH v3 0/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
@ 2018-12-04 21:37 Dan Williams
2018-12-04 21:37 ` [PATCH v3 5/5] " Dan Williams
0 siblings, 1 reply; 3+ messages in thread
From: Dan Williams @ 2018-12-04 21:37 UTC (permalink / raw)
To: tglx
Cc: Sebastian Andrzej Siewior, Peter Zijlstra (Intel), Peter Zijlstra,
Borislav Petkov, Kirill A. Shutemov, Andy Lutomirski, Dave Hansen,
Dave Hansen, stable, x86, linux-kernel
Changes since v2 [1]:
* Fix links in the changelogs to reference lkml.kernel.org instead of
lore.kernel.org (Peter)
* Collect Acked-by's from Kirill and Peter.
* Add more Cc's for patches 1 and 2.
* Strengthen the lead-in comment for the set_p*_safe() helpers (Dave)
[1]: https://lkml.org/lkml/2018/12/1/358
---
>>From patch 5:
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.
Additionally, Dave wanted some runtime assurances that
kernel_physical_mapping_init() is only populating and not changing
existing page table entries. Patches 1 - 4 are implementing a new
set_pte() family of helpers for that purpose.
Patch 5 is tagged for -stable because the false positive warning is now
showing up on 4.19-stable kernels. Patches 1 - 4 are not tagged for
-stable, but if the sanity checking is needed please mark them as such.
The hang that was observed while developing the sanity checking
implementation was resolved by Peter's suggestion to not trigger when
the same pte value is being rewritten.
---
Dan Williams (5):
generic/pgtable: Make {pmd,pud}_same() unconditionally available
generic/pgtable: Introduce {p4d,pgd}_same()
generic/pgtable: Introduce set_pte_safe()
x86/mm: Validate kernel_physical_mapping_init() pte population
x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
arch/x86/include/asm/pgalloc.h | 27 ++++++++++++++
arch/x86/mm/init_64.c | 30 ++++++----------
include/asm-generic/5level-fixup.h | 1 +
include/asm-generic/pgtable-nop4d-hack.h | 1 +
include/asm-generic/pgtable-nop4d.h | 1 +
include/asm-generic/pgtable-nopud.h | 1 +
include/asm-generic/pgtable.h | 56 +++++++++++++++++++++++++-----
7 files changed, 90 insertions(+), 27 deletions(-)
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v3 5/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
2018-12-04 21:37 [PATCH v3 0/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init() Dan Williams
@ 2018-12-04 21:37 ` Dan Williams
2018-12-05 18:07 ` [tip:x86/mm] " tip-bot for Dan Williams
0 siblings, 1 reply; 3+ messages in thread
From: Dan Williams @ 2018-12-04 21:37 UTC (permalink / raw)
To: tglx
Cc: Sebastian Andrzej Siewior, Borislav Petkov, stable,
Andy Lutomirski, Dave Hansen, Peter Zijlstra (Intel),
Kirill A. Shutemov, dave.hansen, x86, linux-kernel
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-B635D72BAC21@amacapital.net
[2]: https://lkml.kernel.org/r/749919a4-cdb1-48a3-adb4-adb81a5fa0b5@intel.com
Fixes: f77084d96355 ("x86/mm/pat: Disable preemption around __flush_tlb_all()")
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@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;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [tip:x86/mm] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
2018-12-04 21:37 ` [PATCH v3 5/5] " Dan Williams
@ 2018-12-05 18:07 ` tip-bot for Dan Williams
0 siblings, 0 replies; 3+ messages in thread
From: tip-bot for Dan Williams @ 2018-12-05 18:07 UTC (permalink / raw)
To: linux-tip-commits
Cc: dave.hansen, linux-kernel, dan.j.williams, torvalds, stable,
mingo, bp, luto, bigeasy, peterz, riel, tglx, kirill.shutemov,
hpa
Commit-ID: ba6f508d0ec4adb09f0a939af6d5e19cdfa8667d
Gitweb: https://git.kernel.org/tip/ba6f508d0ec4adb09f0a939af6d5e19cdfa8667d
Author: Dan Williams <dan.j.williams@intel.com>
AuthorDate: Tue, 4 Dec 2018 13:37:27 -0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 5 Dec 2018 09:03:07 +0100
x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
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-B635D72BAC21@amacapital.net
[2]: https://lkml.kernel.org/r/749919a4-cdb1-48a3-adb4-adb81a5fa0b5@intel.com
[ mingo: Minor readability edits. ]
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@intel.com
Fixes: f77084d96355 ("x86/mm/pat: Disable preemption around __flush_tlb_all()")
Link: http://lkml.kernel.org/r/154395944713.32119.15611079023837132638.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-12-05 18:07 UTC | newest]
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2018-12-04 21:37 [PATCH v3 0/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init() Dan Williams
2018-12-04 21:37 ` [PATCH v3 5/5] " Dan Williams
2018-12-05 18:07 ` [tip:x86/mm] " tip-bot for Dan Williams
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