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031e6e6b4e
For contiguous hugetlb, huge_ptep_set_access_flags performs a
get_clear_flush (which then flushes the TLBs) even when no change of ptes
is necessary.
Unfortunately, this behaviour can lead to back-to-back page faults being
generated when running with multiple threads that access the same
contiguous huge page.
Thread 1 | Thread 2
-----------------------------+------------------------------
hugetlb_fault |
huge_ptep_set_access_flags |
-> invalidate pte range | hugetlb_fault
continue processing | wait for hugetlb_fault_mutex
release mutex and return | huge_ptep_set_access_flags
| -> invalidate pte range
hugetlb_fault
...
This patch changes huge_ptep_set_access_flags s.t. we first read the
contiguous range of ptes (whilst preserving dirty information); the pte
range is only then invalidated where necessary and this prevents further
spurious page faults.
Fixes:
|
||
|---|---|---|
| .. | ||
| cache.S | ||
| context.c | ||
| copypage.c | ||
| dma-mapping.c | ||
| dump.c | ||
| extable.c | ||
| fault.c | ||
| flush.c | ||
| hugetlbpage.c | ||
| init.c | ||
| ioremap.c | ||
| kasan_init.c | ||
| Makefile | ||
| mmap.c | ||
| mmu.c | ||
| numa.c | ||
| pageattr.c | ||
| pgd.c | ||
| physaddr.c | ||
| proc.S | ||
| ptdump_debugfs.c | ||