On Thu, Mar 20, 2025 at 07:52:19PM +0000, Bjoern A. Zeeb wrote: B> He's hitting a ... somewhere in i915kms.ko (here's the two instances I B> have): B> REDZONE: Buffer underflow detected. 16 bytes corrupted before 0xfffffe089bc65000 (262148 bytes allocated). B> REDZONE: Buffer underflow detected. 16 bytes corrupted before 0xfffffe08a7e70000 (262148 bytes allocated).
I looked a bit into the problem and it actually seems very trivial to me. Please re-check my observations. A contigmalloc(9) allocation doesn't get redzone protection, see kern_malloc.c. But free(9) always does contigmalloc check. This makes deprecation of contigfree(9) incompatible with redzone(9). And looks like 19df0c5abcb9d4e951e610b6de98d4d8a00bd5f9 is our first bump into this sad fact. Added reviewers of d1bdc2821fcd416ab9b238580386eb605a6128d0 to Cc. -- Gleb Smirnoff
