Michael Ellerman [off-list ref] writes:

Kunwu Chan [off-list ref] writes:

quoted

Thanks for the reply.

On 2024/2/26 18:49, Michael Ellerman wrote:

quoted

Kunwu Chan [off-list ref] writes:

quoted

This part was commented from commit 6d492ecc6489
("powerpc/THP: Add code to handle HPTE faults for hugepages")
in about 11 years before.

If there are no plans to enable this part code in the future,
we can remove this dead code.

I agree the code can go. But I'd like it to be replaced with a comment
explaining what the dead code was trying to say.

quoted

Thanks, i'll update a new patch with the following comment:
     /*
     * No CPU has hugepages but lacks no execute, so we
     * don't need to worry about cpu no CPU_FTR_COHERENT_ICACHE feature case
     */

Maybe wait until we can get some input from Aneesh. I'm not sure the
code/comment are really up to date.

cheers

How about?

modified   arch/powerpc/mm/book3s64/hash_hugepage.c

@@ -58,17 +58,13 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
 		return 0;
 
 	rflags = htab_convert_pte_flags(new_pmd, flags);
+	/*
+	 * THPs are only supported on platforms that can do mixed page size
+	 * segments (MPSS) and all such platforms have coherent icache. Hence we
+	 * don't need to do lazy icache flush (hash_page_do_lazy_icache()) on
+	 * noexecute fault.
+	 */
 
-#if 0
-	if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
-
-		/*
-		 * No CPU has hugepages but lacks no execute, so we
-		 * don't need to worry about that case
-		 */
-		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
-	}
-#endif
 	/*
 	 * Find the slot index details for this ea, using base page size.
 	 */