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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763630791; bh=O8ppzezBVngh9p2neSkJwi7IKljaPCF/ARYNeHVOvFg=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=nyE0zf7+Zm3qEjzxMy+D6jswoaBimOO39W356YHTZBNMo8zH0aeaxEbym99oYc6gy wLqFIQc4dMFf7rbeeKyEhc5kdWQw6tC/hLcd70clP1tOj3ei8D7BJXc45z1RbBOV7s BgCYKBFbX4iMq8jb/TvSO6gJbQc+Gg36FiHawDAe9k3i26hPvZb3W+gEHATFDqjSNL LVgCVSqbUBOCrmwJdsk4jNUtHGgnlJZwZD0IyIm444iBFesnMNFlH6yCvSWC2f69jg jLoMOC2QlXaBHleNVdIQyjCt+4aWkfdZr+aT4MGJrDmD+3IYR2LJIjQj7JZ0xWybEt R7hLK7DWFIE/w== From: Pratyush Yadav To: Pasha Tatashin Cc: Pratyush Yadav , Andrew Morton , Alexander Graf , Mike Rapoport , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kho: free already restored pages when kho_restore_vmalloc() fails In-Reply-To: (Pasha Tatashin's message of "Tue, 18 Nov 2025 13:43:32 -0500") References: <20251118181811.47336-1-pratyush@kernel.org> Date: Thu, 20 Nov 2025 10:26:28 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 0A6D7140002 X-Rspamd-Server: rspam07 X-Stat-Signature: eaygn717dttnjufg5ajnwdgykfcxb19d X-Rspam-User: X-HE-Tag: 1763630791-669243 X-HE-Meta: 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 R76cPCjt 3uxF3lrTp1eti5zdwvHrZ0blYY4314k3bQg4EgcBxXZmE2Uat8TGMdxsbQf5DFdb1eAnY/m1MfHguJByWCAKmunLPrP9+rHUtYX/S4IqlGEoB1u6z0O5KFA/+5CSMcM7adMem7pC5oQvEHjZ2dH6pTLmm8bZOR2lmY1JNARlYCLeGWjM+m7s5nLyuNA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Nov 18 2025, Pasha Tatashin wrote: >> 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. Hmm, fair point. This patch can be ignored then. -- Regards, Pratyush Yadav