diff options
| author | Mateusz Guzik <mjguzik@gmail.com> | 2025-04-01 16:35:20 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-04-01 22:48:56 +0200 |
| commit | 1701771d3069fbee154ca48e882e227fdcfbb583 (patch) | |
| tree | c32762488e57a5a7f4f04b335fef8250fb55c9c9 | |
| parent | 2b00d9031e42eabc8d32847d231ef48b8be0373d (diff) | |
x86/mm: Stop prefetching current->mm->mmap_lock on page faults
The prefetchw() dates back decades and the fundamental notion of doing
something like this on a lock is shady.
Moreover, for a few years now in the fast path faults are handled with RCU
+ per-vma locking, hopefully not even looking at the lock to begin with.
As such just remove it.
I did not see a point benchmarking this. Given that it is not expected
to be looked at by default justifies not doing the prefetch.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250401143520.1113572-1-mjguzik@gmail.com
| -rw-r--r-- | arch/x86/mm/fault.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 296d294142c8..697432f63c59 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -13,7 +13,6 @@ #include <linux/mmiotrace.h> /* kmmio_handler, ... */ #include <linux/perf_event.h> /* perf_sw_event */ #include <linux/hugetlb.h> /* hstate_index_to_shift */ -#include <linux/prefetch.h> /* prefetchw */ #include <linux/context_tracking.h> /* exception_enter(), ... */ #include <linux/uaccess.h> /* faulthandler_disabled() */ #include <linux/efi.h> /* efi_crash_gracefully_on_page_fault()*/ @@ -1496,8 +1495,6 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) address = cpu_feature_enabled(X86_FEATURE_FRED) ? fred_event_data(regs) : read_cr2(); - prefetchw(¤t->mm->mmap_lock); - /* * KVM uses #PF vector to deliver 'page not present' events to guests * (asynchronous page fault mechanism). The event happens when a |