CVE-2025-71134 — mm/page_alloc: change all pageblocks migrate type on coalescing

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

mm/page_alloc: change all pageblocks migrate type on coalescing

When a page is freed it coalesces with a buddy into a higher order page while possible. When the buddy page migrate type differs, it is expected to be updated to match the one of the page being freed.

However, only the first pageblock of the buddy page is updated, while the rest of the pageblocks are left unchanged.

That causes warnings in later expand() and other code paths (like below), since an inconsistency between migration type of the list containing the page and the page-owned pageblocks migration types is introduced.

[ 308.986589] ------------[ cut here ]------------ [ 308.987227] page type is 0, passed migratetype is 1 (nr=256) [ 308.987275] WARNING: CPU: 1 PID: 5224 at mm/page_alloc.c:812 expand+0x23c/0x270 [ 308.987293] Modules linked in: algif_hash(E) af_alg(E) nft_fib_inet(E) nft_fib_ipv4(E) nft_fib_ipv6(E) nft_fib(E) nft_reject_inet(E) nf_reject_ipv4(E) nf_reject_ipv6(E) nft_reject(E) nft_ct(E) nft_chain_nat(E) nf_nat(E) nf_conntrack(E) nf_defrag_ipv6(E) nf_defrag_ipv4(E) nf_tables(E) s390_trng(E) vfio_ccw(E) mdev(E) vfio_iommu_type1(E) vfio(E) sch_fq_codel(E) drm(E) i2c_core(E) drm_panel_orientation_quirks(E) loop(E) nfnetlink(E) vsock_loopback(E) vmw_vsock_virtio_transport_common(E) vsock(E) ctcm(E) fsm(E) diag288_wdt(E) watchdog(E) zfcp(E) scsi_transport_fc(E) ghash_s390(E) prng(E) aes_s390(E) des_generic(E) des_s390(E…

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CVE-2025-71134 — mm/page_alloc: change all pageblocks migrate type on coalescing