CVE-2026-80862

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

nvme-tcp: fix usage of page frag cache

nvme uses page frag cache to preallocate PDU for each preallocated request of block device. Block devices are created in parallel threads, consequently page frag cache is used in not thread-safe manner. That leads to incorrect refcounting of backstore pages and premature free.

That can be catched by !sendpage ok inside network stack:

WARNING: CPU: 7 PID: 467 at ../net/core/skbuff.c:6931 skb splice from iter+0xfa/0x310. tcp sendmsg locked+0x782/0xce0 tcp sendmsg+0x27/0x40 sock sendmsg+0x8b/0xa0 nvme tcp try send cmd pdu+0x149/0x2a0 Then random panic may occur.

Fix that by serializing the usage of page frag cache.