Don't break the build for a PAGE_SIZE that is not fully supported,
just print out a warning in that case.

Signed-off-by: Igor Belousov <igor.b@beldev.am>
---
 mm/zblock.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/zblock.h b/mm/zblock.h
index fd72961c077a..8610196b651e 100644
--- a/mm/zblock.h
+++ b/mm/zblock.h
@@ -21,7 +21,8 @@
 /* max 256 slots per block, max table size 64 */
 #define SLOT_BITS 8
 #else
-#error Unsupported PAGE_SIZE
+#warn This PAGE_SIZE is not quite supported yet
+#define SLOT_BITS 8
 #endif
 
 #define MAX_SLOTS (1 << SLOT_BITS)
@@ -101,7 +102,7 @@ static const struct block_desc block_desc[] = {
 	{ SLOT_SIZE(10, 3), 10, 3 },
 	{ SLOT_SIZE(9, 3), 9, 3 },
 	{ SLOT_SIZE(4, 2), 4, 2 },
-#elif PAGE_SIZE == 0x4000
+#else
 	{ SLOT_SIZE(255, 0), 255, 0 },
 	{ SLOT_SIZE(185, 0), 185, 0 },
 	{ SLOT_SIZE(145, 0), 145, 0 },
-- 
2.49.0

On Mon, 28 Apr 2025 08:57:27 +0200 Igor Belousov <igor.b@beldev.am> wrote:

> Don't break the build for a PAGE_SIZE that is not fully supported,
> just print out a warning in that case.
> 

I queued these two patches and this fix:

--- a/mm/zblock.h~mm-zblock-avoid-failing-the-build-fix
+++ a/mm/zblock.h
@@ -21,7 +21,7 @@
 /* max 256 slots per block, max table size 64 */
 #define SLOT_BITS 8
 #else
-#warn This PAGE_SIZE is not quite supported yet
+#warning This PAGE_SIZE is not quite supported yet
 #define SLOT_BITS 8
 #endif
 

But please be aware that I consider the zblock zeries to be stuck until
there is clarity that zblock is something we should add to Linux. 
Let's continue to address this in the main thread(s), please.

Or perhaps to restart things, do a full resend after having reworked
the [0/N] changelog to fully address the issues which have thus far
been raised.  And Cc'ing the various individuals who have thus far
commented.

Thanks.

Hi Igor,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Igor-Belousov/mm-zblock-avoid-failing-the-build/20250428-150012
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250428065727.57990-1-igor.b%40beldev.am
patch subject: [PATCH mm-new] mm/zblock: avoid failing the build
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20250428/202504281654.Cj20Gqsl-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250428/202504281654.Cj20Gqsl-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202504281654.Cj20Gqsl-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from mm/zblock.c:27:
>> mm/zblock.h:24:2: error: invalid preprocessing directive #warn; did you mean #warning?
      24 | #warn This PAGE_SIZE is not quite supported yet
         |  ^~~~
         |  warning


vim +24 mm/zblock.h

    16	
    17	#if PAGE_SIZE == 0x1000
    18	/* max 128 slots per block, max table size 32 */
    19	#define SLOT_BITS 7
    20	#elif PAGE_SIZE == 0x4000
    21	/* max 256 slots per block, max table size 64 */
    22	#define SLOT_BITS 8
    23	#else
  > 24	#warn This PAGE_SIZE is not quite supported yet
    25	#define SLOT_BITS 8
    26	#endif
    27	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki