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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762192963; bh=BW3nIFF3ejh4ARubY8O9vgvGP+ux/Zl54hpiB5TaeKA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CP85rxHj43C1QmClK8ydP/bgZqswAFc42oKCQ54TrICWgUj7GK2OkmKpGHZLFDuuv 14CnmrqrWsbN0Tc2NEsq4z4VD1Smh+jmRndB98xJzaJ6Hrqaq3a2QBhNTBQC0vbi2d 9KCzSphtvVWw5jHiwPGcYSxyw9awUJOT/B9B4ruG98mvH8AW6c03H7qnUZGiPc+YsJ K5Uw1ebrjxDlVFP5DYUcL5niMxwv5foGeTmX3JjUh+7YKh06RG1SbV75BqgHSvdX7P o2JO+UpEXblcyaVwJdlve7y55XjhQER/XqgbzXiSDlx9hmbknSJSiEh7O/750ReEi7 +rrOUX2DFlXIQ== From: Pratyush Yadav To: Andrew Morton , Baoquan He , Alexander Graf , Mike Rapoport , Pasha Tatashin , Pratyush Yadav Cc: kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] kho: fix unpreservation of higher-order vmalloc preservations Date: Mon, 3 Nov 2025 19:02:31 +0100 Message-ID: <20251103180235.71409-2-pratyush@kernel.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251103180235.71409-1-pratyush@kernel.org> References: <20251103180235.71409-1-pratyush@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5615620005 X-Stat-Signature: dgsns8t48e58jscz8ms4bsshq3m365tg X-Rspam-User: X-HE-Tag: 1762192964-664510 X-HE-Meta: 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 BpoBC1h3 tUvoBXmzN7vQ5J5yaIBP63RWSGATcSBjBVT03cAu1ei5KFtE+5pYbNPcFFBoldeXg0V2bKtIK6b1yBmfGJTKcZvJ3Hv5o3AZCCumHPuwChTedm5o+6BOhV/NQVZNGLs7mteo7xRAHMgFhqs5mrA1Ce7Vsya55AYKIYqMcwTMcsvmTSnOhYE4m5rmpGRMZ8lj15X/xx5BioEl5pXGDpmedn2vF0GePHkdaMxNSIeF2HV4lq4b923Vxg4GztXjh85nmGT98pFV4Abetwfd7V9+7O48npyxzzXKKLyWF 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: kho_vmalloc_unpreserve_chunk() calls __kho_unpreserve() with end_pfn as pfn + 1. This happens to work for 0-order pages, but leaks higher order pages. For example, say order 2 pages back the allocation. During preservation, they get preserved in the order 2 bitmaps, but kho_vmalloc_unpreserve_chunk() would try to unpreserve them from the order 0 bitmaps, which should not have these bits set anyway, leaving the order 2 bitmaps untouched. This results in the pages being carried over to the next kernel. Nothing will free those pages in the next boot, leaking them. Fix this by taking the order into account when calculating the end PFN for __kho_unpreserve(). Fixes: a667300bd53f2 ("kho: add support for preserving vmalloc allocations") Signed-off-by: Pratyush Yadav --- Notes: When Pasha's patch [0] to add kho_unpreserve_pages() is merged, maybe it would be a better idea to use kho_unpreserve_pages() here? But that is something for later I suppose. [0] https://lore.kernel.org/linux-mm/20251101142325.1326536-4-pasha.tatashin@soleen.com/ kernel/kexec_handover.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index cc5aaa738bc50..c2bcbb10918ce 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -862,7 +862,8 @@ static struct kho_vmalloc_chunk *new_vmalloc_chunk(struct kho_vmalloc_chunk *cur return NULL; } -static void kho_vmalloc_unpreserve_chunk(struct kho_vmalloc_chunk *chunk) +static void kho_vmalloc_unpreserve_chunk(struct kho_vmalloc_chunk *chunk, + unsigned short order) { struct kho_mem_track *track = &kho_out.ser.track; unsigned long pfn = PHYS_PFN(virt_to_phys(chunk)); @@ -871,7 +872,7 @@ static void kho_vmalloc_unpreserve_chunk(struct kho_vmalloc_chunk *chunk) for (int i = 0; i < ARRAY_SIZE(chunk->phys) && chunk->phys[i]; i++) { pfn = PHYS_PFN(chunk->phys[i]); - __kho_unpreserve(track, pfn, pfn + 1); + __kho_unpreserve(track, pfn, pfn + (1 << order)); } } @@ -882,7 +883,7 @@ static void kho_vmalloc_free_chunks(struct kho_vmalloc *kho_vmalloc) while (chunk) { struct kho_vmalloc_chunk *tmp = chunk; - kho_vmalloc_unpreserve_chunk(chunk); + kho_vmalloc_unpreserve_chunk(chunk, kho_vmalloc->order); chunk = KHOSER_LOAD_PTR(chunk->hdr.next); free_page((unsigned long)tmp); -- 2.47.3