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U2FsdGVkX1/X+QRPeizABPrEtDftkIRJaynL16E/NfPXdbvbzGyaQLWjtS4CX9f0sCmTn2XyUayQH1Mc+SeWG4RqxxK5M3eXhwltGDz1lwbGgdYEnnV5/txUl6HlwkzdMjGSqVUIzCC1A+lBQsd2yJ7RYzoxlH5sIhulQlHojLLfJ54O9WAdOdnl6esb4DBF0+/HiyLPOxpYYQKWa6kerqObyBncv1464VFJYcDunTikK2Fhv2uAMWhJJRmnmNpn00xJaSgN7FWftcaKuCcchTuFHh3BNQAzhMXfx+P/1lWSCACldhX3pgFWzz5AqoU869JiXl+t4CojwY59zGqkAS9lfL+LM6vXm/o5vX+tNOFVJOFLhscLTLZi8VFmK6eEL1ZpUXxFFhZr9twRG2HabCbERd9i0PcZ/5Gna+yTB6QAwn+4+x9IP3IRg9lSLonAxjup7i4sPtfttiMqiW8fPvH8v80WtyTDNWTQPH6E/Z8HjQd/dAkW0RA87szPoevyqD3pvSpuzQl963oIrUkSpSMZmDSVdy5+1is1hcpg25GFyqjAJkLurXDq1eGMAkO2RxAVkSL+t+UrOpS1qddfXK8M93b4zxzHhtwUZIG8lh5o7Khwemp9IDoLgddH8MkFvShPfpBKeeZ7R4iRWQuh3gQzDr7S82n2pawLYkn8Qfe3+Vzc/M44nHnOL4Qbr0LDkU+Anf+gKbHWn5kTx2V1R+trwBO/L2rr22l2vuOHOEabuFt3Nk26FAw3m7B6eFzlVH21wYrNeUNkP51wsznkgzT3uaiRkOpEkae+UuujRnF1RQZzvKiKTSEzddAWdAh6ap29DAkXeSaRcPGH7oClx2e9QLtdH0STa+Lx+SGHYUszGtIPOzltT7jeGnbBE8ojmNPwjU0lGfumj9cmXRJajiCST1av+x/xanO1h3Msw2kyRRhefHoUZSeIwhje5GKBQ4OKB+31k8yV1e0Bxjk lG5m2HNO 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Sat Oct 31, 2026 at 10:13 PM EDT, Gregory Price (Meta) wrote: > get_page_from_freelist() and alloc_pages_bulk_noprof() reread > ac->preferred_zoneref->zone at every use. Offlining a zone's last block > rebuilds the zonelists in place, and the shrunk list's NULL terminator > can land on the preferred slot mid-walk: > > CPU 0 CPU 1 > get_page_from_freelist(GFP_KERNEL | __GFP_THISNODE) > zone =3D NORMAL (slot 1) > offline_pages() > build_all_zonelists() > [MOVABLE, NORMAL, NULL] > -> [NORMAL, NULL] > rmqueue(zonelist_zone(slot 1), zone) > zone_statistics(NULL, zone) > > BUG: kernel NULL pointer dereference, address: 0000000000000060 > RIP: 0010:get_page_from_freelist+0x6a5/0x15f0 > Call Trace: > __alloc_frozen_pages_noprof+0x125/0x330 > > Read the slot once. Zones are never freed, so a stale zone is safe, and > a NULL slot fails the same way as walking off the end. > > Fixes: 11cd8638c37f ("mm, page_alloc: remove stop_machine from build_all_= zonelists") > Cc: stable@vger.kernel.org > Signed-off-by: Gregory Price (Meta) > Reviewed-by: Vlastimil Babka (SUSE) > --- > mm/page_alloc.c | 31 +++++++++++++++++++++++-------- > 1 file changed, 23 insertions(+), 8 deletions(-) > Makes sense. Acked-by: Zi Yan --=20 Best Regards, Yan, Zi