linux-kernel - Re: [PATCH] kho: free already restored pages when kho_restore

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Message-ID: <CA+CK2bAumctR3WyDW0b+NeeX22+OuCMkQ2VsGvnE1NxJwOVPEQ@mail.gmail.com>
Date: Tue, 18 Nov 2025 13:43:32 -0500
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: Pratyush Yadav <pratyush@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Alexander Graf <graf@...zon.com>, 
	Mike Rapoport <rppt@...nel.org>, kexec@...ts.infradead.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kho: free already restored pages when kho_restore_vmalloc()
 fails

> When kho_restore_vmalloc() fails, it frees up the pages array, but not
> the pages it contains. These are the pages that were successfully
> restored using kho_restore_pages(). If the failure happens when
> restoring the pages, the ones successfully restored are leaked. If the
> failure happens when allocating the vm_area or when mapping the pages,
> all the pages of the preserved vmalloc buffer are leaked.

Hm, I am not sure if KHO should be responsible for freeing the
restored pages. We don't know the content of those pages, and what
they are used for. They could be used by a hypervisor or a device.
Therefore, it may be better to keep them leaked, and let the caller
decide what to do next: i.e., boot into a maintenance mode, crash the
kernel, or allow the leak until the next reboot.

Pasha