* Re: [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory
2026-01-22 13:27 [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory ranxiaokai627
@ 2026-01-22 13:35 ` Pratyush Yadav
2026-01-22 18:09 ` Pasha Tatashin
2026-01-23 8:55 ` Mike Rapoport
2 siblings, 0 replies; 4+ messages in thread
From: Pratyush Yadav @ 2026-01-22 13:35 UTC (permalink / raw)
To: ranxiaokai627
Cc: pratyush, surenb, akpm, pasha.tatashin, kent.overstreet, rppt,
graf, linux-mm, linux-kernel, kexec, ran.xiaokai, stable
On Thu, Jan 22 2026, ranxiaokai627@163.com wrote:
> From: Ran Xiaokai <ran.xiaokai@zte.com.cn>
>
> Memblock pages (including reserved memory) should have their allocation
> tags initialized to CODETAG_EMPTY via clear_page_tag_ref() before being
> released to the page allocator. When kho restores pages through
> kho_restore_page(), missing this call causes mismatched
> allocation/deallocation tracking and below warning message:
>
> alloc_tag was not set
> WARNING: include/linux/alloc_tag.h:164 at ___free_pages+0xb8/0x260, CPU#1: swapper/0/1
> RIP: 0010:___free_pages+0xb8/0x260
> kho_restore_vmalloc+0x187/0x2e0
> kho_test_init+0x3c4/0xa30
> do_one_initcall+0x62/0x2b0
> kernel_init_freeable+0x25b/0x480
> kernel_init+0x1a/0x1c0
> ret_from_fork+0x2d1/0x360
>
> Add missing clear_page_tag_ref() annotation in kho_restore_page() to
> fix this.
>
> Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
> ---
>
> v2 -> v3:
> - also call clear_page_tag_ref() for non-compound order-0 tail pages
>
> kernel/liveupdate/kexec_handover.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
> index d4482b6e3cae..96767b106cac 100644
> --- a/kernel/liveupdate/kexec_handover.c
> +++ b/kernel/liveupdate/kexec_handover.c
> @@ -255,6 +255,14 @@ static struct page *kho_restore_page(phys_addr_t phys, bool is_folio)
> if (is_folio && info.order)
> prep_compound_page(page, info.order);
>
> + /* Always mark headpage's codetag as empty to avoid accounting mismatch */
> + clear_page_tag_ref(page);
> + if (!is_folio) {
> + /* Also do that for the non-compound tail pages */
> + for (unsigned int i = 1; i < nr_pages; i++)
> + clear_page_tag_ref(page + i);
> + }
> +
I think it would be a little bit better if we just did this in the loop
above instead of looping again. But I think it is fine for now. I can
fix it up in the next release.
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
> adjust_managed_page_count(page, nr_pages);
> return page;
> }
--
Regards,
Pratyush Yadav
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory
2026-01-22 13:27 [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory ranxiaokai627
2026-01-22 13:35 ` Pratyush Yadav
@ 2026-01-22 18:09 ` Pasha Tatashin
2026-01-23 8:55 ` Mike Rapoport
2 siblings, 0 replies; 4+ messages in thread
From: Pasha Tatashin @ 2026-01-22 18:09 UTC (permalink / raw)
To: ranxiaokai627
Cc: pratyush, surenb, akpm, kent.overstreet, rppt, graf, linux-mm,
linux-kernel, kexec, ran.xiaokai, stable
On Thu, Jan 22, 2026 at 8:28 AM <ranxiaokai627@163.com> wrote:
>
> From: Ran Xiaokai <ran.xiaokai@zte.com.cn>
>
> Memblock pages (including reserved memory) should have their allocation
> tags initialized to CODETAG_EMPTY via clear_page_tag_ref() before being
> released to the page allocator. When kho restores pages through
> kho_restore_page(), missing this call causes mismatched
> allocation/deallocation tracking and below warning message:
>
> alloc_tag was not set
> WARNING: include/linux/alloc_tag.h:164 at ___free_pages+0xb8/0x260, CPU#1: swapper/0/1
> RIP: 0010:___free_pages+0xb8/0x260
> kho_restore_vmalloc+0x187/0x2e0
> kho_test_init+0x3c4/0xa30
> do_one_initcall+0x62/0x2b0
> kernel_init_freeable+0x25b/0x480
> kernel_init+0x1a/0x1c0
> ret_from_fork+0x2d1/0x360
>
> Add missing clear_page_tag_ref() annotation in kho_restore_page() to
> fix this.
>
> Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
> ---
>
> v2 -> v3:
> - also call clear_page_tag_ref() for non-compound order-0 tail pages
>
> kernel/liveupdate/kexec_handover.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
> index d4482b6e3cae..96767b106cac 100644
> --- a/kernel/liveupdate/kexec_handover.c
> +++ b/kernel/liveupdate/kexec_handover.c
> @@ -255,6 +255,14 @@ static struct page *kho_restore_page(phys_addr_t phys, bool is_folio)
> if (is_folio && info.order)
> prep_compound_page(page, info.order);
>
> + /* Always mark headpage's codetag as empty to avoid accounting mismatch */
> + clear_page_tag_ref(page);
> + if (!is_folio) {
> + /* Also do that for the non-compound tail pages */
> + for (unsigned int i = 1; i < nr_pages; i++)
> + clear_page_tag_ref(page + i);
> + }
> +
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Pasha
> adjust_managed_page_count(page, nr_pages);
> return page;
> }
> --
> 2.25.1
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory
2026-01-22 13:27 [PATCH RESEND v3] kho: init alloc tags when restoring pages from reserved memory ranxiaokai627
2026-01-22 13:35 ` Pratyush Yadav
2026-01-22 18:09 ` Pasha Tatashin
@ 2026-01-23 8:55 ` Mike Rapoport
2 siblings, 0 replies; 4+ messages in thread
From: Mike Rapoport @ 2026-01-23 8:55 UTC (permalink / raw)
To: ranxiaokai627
Cc: pratyush, surenb, akpm, pasha.tatashin, kent.overstreet, graf,
linux-mm, linux-kernel, kexec, ran.xiaokai, stable
On Thu, Jan 22, 2026 at 01:27:40PM +0000, ranxiaokai627@163.com wrote:
> From: Ran Xiaokai <ran.xiaokai@zte.com.cn>
>
> Memblock pages (including reserved memory) should have their allocation
> tags initialized to CODETAG_EMPTY via clear_page_tag_ref() before being
> released to the page allocator. When kho restores pages through
> kho_restore_page(), missing this call causes mismatched
> allocation/deallocation tracking and below warning message:
>
> alloc_tag was not set
> WARNING: include/linux/alloc_tag.h:164 at ___free_pages+0xb8/0x260, CPU#1: swapper/0/1
> RIP: 0010:___free_pages+0xb8/0x260
> kho_restore_vmalloc+0x187/0x2e0
> kho_test_init+0x3c4/0xa30
> do_one_initcall+0x62/0x2b0
> kernel_init_freeable+0x25b/0x480
> kernel_init+0x1a/0x1c0
> ret_from_fork+0x2d1/0x360
>
> Add missing clear_page_tag_ref() annotation in kho_restore_page() to
> fix this.
>
> Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
>
> v2 -> v3:
> - also call clear_page_tag_ref() for non-compound order-0 tail pages
>
> kernel/liveupdate/kexec_handover.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
> index d4482b6e3cae..96767b106cac 100644
> --- a/kernel/liveupdate/kexec_handover.c
> +++ b/kernel/liveupdate/kexec_handover.c
> @@ -255,6 +255,14 @@ static struct page *kho_restore_page(phys_addr_t phys, bool is_folio)
> if (is_folio && info.order)
> prep_compound_page(page, info.order);
>
> + /* Always mark headpage's codetag as empty to avoid accounting mismatch */
> + clear_page_tag_ref(page);
> + if (!is_folio) {
> + /* Also do that for the non-compound tail pages */
> + for (unsigned int i = 1; i < nr_pages; i++)
> + clear_page_tag_ref(page + i);
> + }
> +
> adjust_managed_page_count(page, nr_pages);
> return page;
> }
> --
> 2.25.1
>
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 4+ messages in thread