On Thu, Sep 23, 2021 at 11:47:48AM +0200, Christophe Leroy wrote:

Le 23/09/2021 à 09:43, Mike Rapoport a écrit :

quoted

From: Mike Rapoport <redacted>

For ages memblock_free() interface dealt with physical addresses even
despite the existence of memblock_alloc_xx() functions that return a
virtual pointer.

Introduce memblock_phys_free() for freeing physical ranges and repurpose
memblock_free() to free virtual pointers to make the following pairing
abundantly clear:

	int memblock_phys_free(phys_addr_t base, phys_addr_t size);
	phys_addr_t memblock_phys_alloc(phys_addr_t base, phys_addr_t size);

	void *memblock_alloc(phys_addr_t size, phys_addr_t align);
	void memblock_free(void *ptr, size_t size);

Replace intermediate memblock_free_ptr() with memblock_free() and drop
unnecessary aliases memblock_free_early() and memblock_free_early_nid().

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mike Rapoport <redacted>
---

quoted

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 1a04e5bdf655..37826d8c4f74 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c

@@ -723,7 +723,7 @@ void __init smp_save_dump_cpus(void)
  			/* Get the CPU registers */
  			smp_save_cpu_regs(sa, addr, is_boot_cpu, page);
  	}
-	memblock_free(page, PAGE_SIZE);
+	memblock_phys_free(page, PAGE_SIZE);
  	diag_amode31_ops.diag308_reset();
  	pcpu_set_smt(0);
  }

@@ -880,7 +880,7 @@ void __init smp_detect_cpus(void)
  	/* Add CPUs present at boot */
  	__smp_rescan_cpus(info, true);
-	memblock_free_early((unsigned long)info, sizeof(*info));
+	memblock_free(info, sizeof(*info));
  }
  /*

I'm a bit lost. IIUC memblock_free_early() and memblock_free() where
identical.

Yes, they were, but all calls to memblock_free_early() were using
__pa(vaddr) because they had a virtual address at hand.

In the first hunk memblock_free() gets replaced by memblock_phys_free()
In the second hunk memblock_free_early() gets replaced by memblock_free()

In the first hunk the memory is allocated with memblock_phys_alloc() and we
have a physical range to free. In the second hunk the memory is allocated
with memblock_alloc() and we are freeing a virtual pointer.
 

I think it would be easier to follow if you could split it in several
patches:

It was an explicit request from Linus to make it a single commit:

  but the actual commit can and should be just a single commit that just
  fixes 'memblock_free()' to have sane interfaces.

I don't feel strongly about splitting it (except my laziness really
objects), but I don't think doing the conversion in several steps worth the
churn.

- First patch: Create memblock_phys_free() and change all relevant
memblock_free() to memblock_phys_free() - Or change memblock_free() to
memblock_phys_free() and make memblock_free() an alias of it.
- Second patch: Make memblock_free_ptr() become memblock_free() and change
all remaining callers to the new semantics (IIUC memblock_free(__pa(ptr))
becomes memblock_free(ptr) and make memblock_free_ptr() an alias of
memblock_free()
- Fourth patch: Replace and drop memblock_free_ptr()
- Fifth patch: Drop memblock_free_early() and memblock_free_early_nid() (All
users should have been upgraded to memblock_free_phys() in patch 1 or
memblock_free() in patch 2)

Christophe

-- 
Sincerely yours,
Mike.