linux-kernel - Re: [PATCH v5 3/4] kho: add support for preserving vmalloc allocations

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Message-ID: <mafs0a52idbeg.fsf@kernel.org>
Date: Thu, 25 Sep 2025 13:22:47 +0200
From: Pratyush Yadav <pratyush@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Pratyush Yadav <pratyush@...nel.org>,  Jason Gunthorpe <jgg@...dia.com>,
  Mike Rapoport <rppt@...nel.org>,  Alexander Graf <graf@...zon.com>,
  Baoquan He <bhe@...hat.com>,  Changyuan Lyu <changyuanl@...gle.com>,
  Chris Li <chrisl@...nel.org>,  Pasha Tatashin
 <pasha.tatashin@...een.com>,  kexec@...ts.infradead.org,
  linux-mm@...ck.org,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/4] kho: add support for preserving vmalloc allocations

On Wed, Sep 24 2025, Andrew Morton wrote:

> On Wed, 24 Sep 2025 17:28:07 +0200 Pratyush Yadav <pratyush@...nel.org> wrote:
>
>> >
>> > Not sure why this code works - I'll suspend the series from linux-next
>> > for now.
>> 
>> It only gets called in the error path and that didn't get hit during
>> testing I suppose. Until v3 the chunk was being allocated using
>> kzalloc() so I guess this got missed in the move to get_zeroed_page().
>> 
>> I think Mike is out of office this week. Do you think this series is
>> stable enough to land in the upcoming merge window? If so, I can send a
>> v6 with the fix today.
>
> A one-liner fiup would be preferred, if no other changes are required,
> thanks.

--- 8< ---
>From f746718a99da3c670089a42f7c59660b455f265d Mon Sep 17 00:00:00 2001
From: Pratyush Yadav <pratyush@...nel.org>
Date: Thu, 25 Sep 2025 13:05:08 +0200
Subject: [PATCH] fixup! kho: add support for preserving vmalloc allocations

Chunks are allocated using get_zeroed_page() so they should be freed
using free_page() not kfree().

Signed-off-by: Pratyush Yadav <pratyush@...nel.org>
---
 kernel/kexec_handover.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c
index e6380d8dce574..d06ca232683cd 100644
--- a/kernel/kexec_handover.c
+++ b/kernel/kexec_handover.c
@@ -885,7 +885,7 @@ static void kho_vmalloc_free_chunks(struct kho_vmalloc *kho_vmalloc)
 		kho_vmalloc_unpreserve_chunk(chunk);
 
 		chunk = KHOSER_LOAD_PTR(chunk->hdr.next);
-		kfree(tmp);
+		free_page((unsigned long)tmp);
 	}
 }
 
-- 
2.47.3