Searched hist:"8 f1d56f6" (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/arch/x86/include/asm/ |
| H A D | tlbflush.h | 8f1d56f6 Sun Jul 10 18:28:37 CDT 2022 Nadav Amit <namit@vmware.com> x86/mm/tlb: Ignore f->new_tlb_gen when zero
Commit aa44284960d5 ("x86/mm/tlb: Avoid reading mm_tlb_gen when
possible") introduced an optimization to skip superfluous TLB
flushes based on the generation provided in flush_tlb_info.
However, arch_tlbbatch_flush() does not provide any generation in
flush_tlb_info and populates the flush_tlb_info generation with
0. This 0 is causes the flush_tlb_info to be interpreted as a
superfluous, old flush. As a result, try_to_unmap_one() would
not perform any TLB flushes.
Fix it by checking whether f->new_tlb_gen is nonzero. Zero value
is anyhow is an invalid generation value. To avoid future
confusion, introduce TLB_GENERATION_INVALID constant and use it
properly. Add warnings to ensure no partial flushes are done with
TLB_GENERATION_INVALID or when f->mm is NULL, since this does not
make any sense.
In addition, add the missing unlikely().
[ dhansen: change VM_BUG_ON() -> VM_WARN_ON(), clarify changelog ]
Fixes: aa44284960d5 ("x86/mm/tlb: Avoid reading mm_tlb_gen when possible")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Hugh Dickins <hughd@google.com>
Link: https://lkml.kernel.org/r/20220710232837.3618-1-namit@vmware.com
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| /openbmc/linux/arch/x86/mm/ |
| H A D | tlb.c | 8f1d56f6 Sun Jul 10 18:28:37 CDT 2022 Nadav Amit <namit@vmware.com> x86/mm/tlb: Ignore f->new_tlb_gen when zero
Commit aa44284960d5 ("x86/mm/tlb: Avoid reading mm_tlb_gen when
possible") introduced an optimization to skip superfluous TLB
flushes based on the generation provided in flush_tlb_info.
However, arch_tlbbatch_flush() does not provide any generation in
flush_tlb_info and populates the flush_tlb_info generation with
0. This 0 is causes the flush_tlb_info to be interpreted as a
superfluous, old flush. As a result, try_to_unmap_one() would
not perform any TLB flushes.
Fix it by checking whether f->new_tlb_gen is nonzero. Zero value
is anyhow is an invalid generation value. To avoid future
confusion, introduce TLB_GENERATION_INVALID constant and use it
properly. Add warnings to ensure no partial flushes are done with
TLB_GENERATION_INVALID or when f->mm is NULL, since this does not
make any sense.
In addition, add the missing unlikely().
[ dhansen: change VM_BUG_ON() -> VM_WARN_ON(), clarify changelog ]
Fixes: aa44284960d5 ("x86/mm/tlb: Avoid reading mm_tlb_gen when possible")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Hugh Dickins <hughd@google.com>
Link: https://lkml.kernel.org/r/20220710232837.3618-1-namit@vmware.com
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