Re: [PATCH 1/2] mm/page-flags: Define HWPoison test-and-change helpers unconditionally

[Kaitao Cheng]

在 2026/9/26 14:19, Andrew Morton 写道:
> On Mon, 7 Sep 2026 17:42:11 +0200 "David Hildenbrand (Arm)" <david@xxxxxxxxxx> wrote:
> 
>> On 9/3/26 07:35, Kaitao Cheng wrote:
>>> From: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
>>>
>>> Page flag helpers for configuration-dependent flags provide false or no-op
>>> variants so that their users can be independent of the configuration.
>>>
>>> The HWPoison helpers do not fully follow this pattern. When
>>> CONFIG_MEMORY_FAILURE is enabled, PAGEFLAG() and TESTSCFLAG() provide the
>>> regular, test-and-set, and test-and-clear operations. When it is disabled,
>>> only PAGEFLAG_FALSE() is instantiated, leaving TestSetPageHWPoison() and
>>> TestClearPageHWPoison() undefined.
>>>
>>> Use TESTSCFLAG_FALSE() to provide the missing accessors when memory failure
>>> handling is disabled. Both accessors return false, which is consistent with
>>> HWPoison state being unavailable, and makes the accessor interface
>>> consistent across configurations.
>>>
>>> Signed-off-by: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
>>> ---
>>>  include/linux/page-flags.h | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
>>> index 7a863572adce..a2315ab1dd3a 100644
>>> --- a/include/linux/page-flags.h
>>> +++ b/include/linux/page-flags.h
>>> @@ -656,6 +656,7 @@ TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
>>>  #define __PG_HWPOISON (1UL << PG_hwpoison)
>>>  #else
>>>  PAGEFLAG_FALSE(HWPoison, hwpoison)
>>> +TESTSCFLAG_FALSE(HWPoison, hwpoison)
>>>  #define __PG_HWPOISON 0
>>>  #endif
>>>  
>>
>> Can we just squash this patch into #2 please?
> 
> I did that.

I’ve also posted a v2 version.
https://lore.kernel.org/all/20260923055318.57485-1-kaitao.cheng@xxxxxxxxx/

> 
> From: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
> Subject: mm/page-flags: define HWPoison test-and-change helpers unconditionally
> Date: Thu, 3 Sep 2026 13:35:34 +0800
> 
> Page flag helpers for configuration-dependent flags provide false or no-op
> variants so that their users can be independent of the configuration.
> 
> The HWPoison helpers do not fully follow this pattern.  When
> CONFIG_MEMORY_FAILURE is enabled, PAGEFLAG() and TESTSCFLAG() provide the
> regular, test-and-set, and test-and-clear operations.  When it is
> disabled, only PAGEFLAG_FALSE() is instantiated, leaving
> TestSetPageHWPoison() and TestClearPageHWPoison() undefined.
> 
> Use TESTSCFLAG_FALSE() to provide the missing accessors when memory
> failure handling is disabled.  Both accessors return false, which is
> consistent with HWPoison state being unavailable, and makes the accessor
> interface consistent across configurations.
> 
> Also remove now-unneeded test_and_clear_pmem_poison() from nvdimm/pmem.
> 
> Link: https://lore.kernel.org/20260903053535.17611-1-kaitao.cheng@xxxxxxxxx
> Link: https://lore.kernel.org/20260903053535.17611-2-kaitao.cheng@xxxxxxxxx
> Link: https://lore.kernel.org/20260903053535.17611-3-kaitao.cheng@xxxxxxxxx
> Signed-off-by: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Acked-by: Muchun Song <muchun.song@xxxxxxxxx>
> Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Alison Schofield <alison.schofield@xxxxxxxxx>
> Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
> Cc: Liam R. Howlett <liam@xxxxxxxxxxxxx>
> Cc: Lorenzo Stoakes <ljs@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxxxxx>
> Cc: Ira Weiny <iweiny@xxxxxxxxxx>
> ---
> 
>  drivers/nvdimm/pmem.c      |    2 +-
>  drivers/nvdimm/pmem.h      |   12 ------------
>  include/linux/page-flags.h |    1 +
>  3 files changed, 2 insertions(+), 13 deletions(-)
> 
> --- a/include/linux/page-flags.h~mm-page-flags-define-hwpoison-test-and-change-helpers-unconditionally
> +++ a/include/linux/page-flags.h
> @@ -655,6 +655,7 @@ TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
>  #define __PG_HWPOISON (1UL << PG_hwpoison)
>  #else
>  PAGEFLAG_FALSE(HWPoison, hwpoison)
> +TESTSCFLAG_FALSE(HWPoison, hwpoison)
>  #define __PG_HWPOISON 0
>  #endif
>  
> --- a/drivers/nvdimm/pmem.c~mm-page-flags-define-hwpoison-test-and-change-helpers-unconditionally
> +++ a/drivers/nvdimm/pmem.c
> @@ -80,7 +80,7 @@ static void pmem_mkpage_present(struct p
>  		 * here since we're in the driver I/O path and
>  		 * outstanding I/O requests pin the dev_pagemap.
>  		 */
> -		if (test_and_clear_pmem_poison(page))
> +		if (TestClearPageHWPoison(page))
>  			clear_mce_nospec(pfn);
>  	}
>  }
> --- a/drivers/nvdimm/pmem.h~mm-page-flags-define-hwpoison-test-and-change-helpers-unconditionally
> +++ a/drivers/nvdimm/pmem.h
> @@ -1,7 +1,6 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
>  #ifndef __NVDIMM_PMEM_H__
>  #define __NVDIMM_PMEM_H__
> -#include <linux/page-flags.h>
>  #include <linux/badblocks.h>
>  #include <linux/memremap.h>
>  #include <linux/types.h>
> @@ -31,15 +30,4 @@ long __pmem_direct_access(struct pmem_de
>  		long nr_pages, enum dax_access_mode mode, void **kaddr,
>  		unsigned long *pfn);
>  
> -#ifdef CONFIG_MEMORY_FAILURE
> -static inline bool test_and_clear_pmem_poison(struct page *page)
> -{
> -	return TestClearPageHWPoison(page);
> -}
> -#else
> -static inline bool test_and_clear_pmem_poison(struct page *page)
> -{
> -	return false;
> -}
> -#endif
>  #endif /* __NVDIMM_PMEM_H__ */
> _

-- 
Thanks
Kaitao Cheng