On 05/29/2013 07:33 PM, Catalin Marinas wrote: > On Wed, May 29, 2013 at 01:56:13PM +0100, Vineet Gupta wrote: >> zap_pte_range loops from @addr to @end. In the middle, if it runs out of >> batching slots, TLB entries needs to be flushed for @start to @interim, >> NOT @interim to @end. >> >> Since ARC port doesn't use page free batching I can't test it myself but >> this seems like the right thing to do. >> Observed this when working on a fix for the issue at thread: >> http://www.spinics.net/lists/linux-arch/msg21736.html >> >> Signed-off-by: Vineet Gupta <[email protected]> >> Cc: Andrew Morton <[email protected]> >> Cc: Mel Gorman <[email protected]> >> Cc: Hugh Dickins <[email protected]> >> Cc: Rik van Riel <[email protected]> >> Cc: David Rientjes <[email protected]> >> Cc: Peter Zijlstra <[email protected]> >> Cc: [email protected] >> Cc: [email protected] <[email protected]> >> Cc: Catalin Marinas <[email protected]> >> Cc: Max Filippov <[email protected]> >> --- >> mm/memory.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index 6dc1882..d9d5fd9 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -1110,6 +1110,7 @@ static unsigned long zap_pte_range(struct mmu_gather >> *tlb, >> spinlock_t *ptl; >> pte_t *start_pte; >> pte_t *pte; >> + unsigned long range_start = addr; >> >> again: >> init_rss_vec(rss); >> @@ -1215,12 +1216,14 @@ again: >> force_flush = 0; >> >> #ifdef HAVE_GENERIC_MMU_GATHER >> - tlb->start = addr; >> - tlb->end = end; >> + tlb->start = range_start; >> + tlb->end = addr; >> #endif >> tlb_flush_mmu(tlb); >> - if (addr != end) >> + if (addr != end) { >> + range_start = addr; >> goto again; >> + } >> } > Isn't this code only run if force_flush != 0? force_flush is set to > !__tlb_remove_page() and this function always returns 1 on (generic TLB) > UP since tlb_fast_mode() is 1. There is no batching on UP with the > generic TLB code.
Correct ! That's why the changelog says I couldn't test it on ARC port itself :-) However based on the other discussion (Max's TLB/PTE inconsistency), as I started writing code to reuse this block to flush the TLB even for non forced case, I realized that what this is doing is incorrect and won't work for the general flushing. Ignoring all other threads, do we agree that the exiting code - if used in any situations is incorrect semantically ? -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
