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b=bX6Niq2fCvU2FntF15yZDWJ/6kd2Cd766Rcq3gRZajZ7zH3dwUYzJXmr3v8Ej0VpI Y+ZtIqhAupEVlrXQmQ8VS3DghuyFB5ZRtY0zXOhvSgnMw97KPaucJzr4KinUEczUZt vbwJSi8fzOpDoIxZJa5Skk/0FyALPGDeCO96pXFXimupZpphGc0JKQEtmSQ/bi3c3V 7kEbSX0DJbwviS1cRP2J1VRrqS2AdpcLykzDmygRjkuduwfIPwBPhsAnu2Jf+JO97C QPFjR8EZgaVOY4z2jDxxSJMLj/PyyrwZLTSwAQS55NRu/jGwNQ+TDD1mCHqRNGdOFf Rh+gML+PhNJ0Q== From: Pratyush Yadav To: Evangelos Petrongonas Cc: Pratyush Yadav , "Mike Rapoport (Microsoft)" , Alexander Graf , Pasha Tatashin , Rob Herring , Saravana Kannan , Changyuan Lyu , Andrew Morton , , , , Subject: Re: [PATCH v2] kho: skip KHO for crash kernel In-Reply-To: <20260416161744.GA65710@dev-dsk-epetron-1c-1d4d9719.eu-west-1.amazon.com> (Evangelos Petrongonas's message of "Thu, 16 Apr 2026 16:17:44 +0000") References: <20260410011609.1103-1-epetron@amazon.de> <2vxztstf7ys7.fsf@kernel.org> <20260416161744.GA65710@dev-dsk-epetron-1c-1d4d9719.eu-west-1.amazon.com> Date: Thu, 16 Apr 2026 16:40:39 +0000 Message-ID: <2vxz8qam7ta0.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Stat-Signature: g5tkjagokzdyszzhp4b1t3o5oapo5ra1 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8882A180010 X-Rspam-User: X-HE-Tag: 1776357644-331501 X-HE-Meta: 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 4saKgHLQ dHKAcxkZB53Ofasw99Uj6aRXNDPbUxky4BaXWduYXq4+BHvMDUh1PxMqo5tlun5BAsmgOd8SJ4BJC0PHJVkzG/UkcBY7YX/0MfSsUuHny4+6GacYEvvoBjm47nHjAO+itSGDSWO0DW7G2s/s6+UvYybWlng4XrqrKYSEWo25f45Lrasc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 16 2026, Evangelos Petrongonas wrote: > On Mon, Apr 13, 2026 at 01:52:40PM +0000 Pratyush Yadav wrote: >> Hi Evangelos, >> >> On Fri, Apr 10 2026, Evangelos Petrongonas wrote: [...] >> > Note regarding backporting >> > The offending commit was deployed with 6.19. The only other supported >> > kernel version with 6.18, unless I miss someting uses >> > ``` >> > if (!kho_out.finalized) >> > ``` >> > which in the case of crash kernel it shouldn't be finalised. >> >> While normally you should load the crash kernel early in boot and at >> that point KHO should not be finalized, I don't see anything that >> prevents crash kernel from being loaded after finalize. In which case, >> you can trigger this bug before d7255959b69a ("kho: allow kexec load >> before KHO finalization") as well. Also, before f322a97aeb2a ("kho: only >> fill kimage if KHO is finalized") (landed in v6.18) kho_fill_kimage() >> was also guarded by if (!kho_enable). So you'd hit this bug in all >> kernels before that point in the very same way as today. >> >> So should we update Fixes to 3bdecc3c93f9 ("kexec: add KHO support to >> kexec file loads") and Cc stable? >> > But in this case it seems a userspace misuse if it finalizes kho for > crash kernel. Whereas with the current state we hit the bug with a sane > userspace. Yeap we would hit that in earlier kernel than 6.18, but none > with KHO is supported is it? > > I don't have strong objection for backporting it to 6.18, but it feels > unnecessary. Fair enough. Let's leave it as it is then. [...] -- Regards, Pratyush Yadav