Re: [PATCH v1] mm: page_alloc: Add debug log in free_reserved_area for static memory

On 28.09.21 12:53, Faiyaz Mohammed wrote:

On 9/28/2021 4:09 PM, David Hildenbrand wrote:

quoted

On 28.09.21 11:04, Faiyaz Mohammed wrote:

quoted

For INITRD and initmem memory is reserved through "memblock_reserve"
during boot up but it is free via "free_reserved_area" instead
of "memblock_free".
For example:
[    0.294848] Freeing initrd memory: 12K.
[    0.696688] Freeing unused kernel memory: 4096K.

To get the start and end address of the above freed memory and to account
proper memblock added memblock_dbg log in "free_reserved_area".
After adding log:
[    0.294837] memblock_free: [0x00000083600000-0x00000083603000]
free_initrd_mem+0x20/0x28
[    0.294848] Freeing initrd memory: 12K.
[    0.695246] memblock_free: [0x00000081600000-0x00000081a00000]
free_initmem+0x70/0xc8
[    0.696688] Freeing unused kernel memory: 4096K.

Signed-off-by: Faiyaz Mohammed <redacted>
---
   mm/page_alloc.c | 5 +++++
   1 file changed, 5 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b37435c..f85c3b2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -8129,6 +8129,11 @@ unsigned long free_reserved_area(void *start,

void *end, int poison, const char
           pr_info("Freeing %s memory: %ldK\n",
               s, pages << (PAGE_SHIFT - 10));
   +#ifdef CONFIG_HAVE_MEMBLOCK
+        memblock_dbg("memblock_free: [%#016llx-%#016llx] %pS\n",
+            __pa(start), __pa(end), (void *)_RET_IP_);
+#endif

IMHO, the "memblock_free" part is misleading. Something was allocated
early via memblock, then we transitioned to the buddy, now we're freeing
that early allocation via the buddy.
Yes, we're freeing the early allocation via buddy, but for proper

memblock accounting we need this debug print.

What do you mean with "accounting" ? These are debug statements.


-- 
Thanks,

David / dhildenb