From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx> This reverts commit 9e46e4dcd9d6cd88342b028dbfa5f4fb7483d39c. kbuild reports a warning in memblock_remove_region() because of a false positive caused by partial reset of the memblock state. Doing the full reset will remove the false positives, but will allow late use of memblock_free() to go unnoticed, so it is better to revert the offending commit. WARNING: CPU: 0 PID: 1 at mm/memblock.c:352 memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1)) Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc3-00001-g9e46e4dcd9d6 #2 RIP: 0010:memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1)) Code: 00 00 48 8b 43 18 48 c7 40 08 00 00 00 00 48 8b 43 18 c7 40 10 00 00 00 00 48 8b 43 18 c7 40 14 00 04 00 00 5b c3 cc cc cc cc <0f> 0b eb c2 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 RSP: 0000:ffa0000000077e78 EFLAGS: 00010206 RAX: ffffffff82f4bc40 RBX: ffffffff82f4bc18 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff82f4bc58 RDI: ffffffff82f4bc40 RBP: 0000000000000000 R08: ff1100207ffd4d00 R09: 0000000000000002 R10: ffd4000081ff9d00 R11: ff1100207ffd4000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ff1100103f200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ff1100207fc00000 CR3: 000000207ea18001 CR4: 0000000000771ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1)) ? __warn (kbuild/src/x86_64/kernel/panic.c:673) ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1)) ? report_bug (kbuild/src/x86_64/lib/bug.c:180 kbuild/src/x86_64/lib/bug.c:219) ? handle_bug (kbuild/src/x86_64/arch/x86/kernel/traps.c:324) ? exc_invalid_op (kbuild/src/x86_64/arch/x86/kernel/traps.c:345 (discriminator 1)) ? asm_exc_invalid_op (kbuild/src/x86_64/arch/x86/include/asm/idtentry.h:568) ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:352 (discriminator 1)) ? memblock_remove_region (kbuild/src/x86_64/mm/memblock.c:348) memblock_discard (kbuild/src/x86_64/mm/memblock.c:383) page_alloc_init_late (kbuild/src/x86_64/include/linux/find.h:208 kbuild/src/x86_64/include/linux/nodemask.h:266 kbuild/src/x86_64/mm/mm_init.c:2405) kernel_init_freeable (kbuild/src/x86_64/init/main.c:1325 kbuild/src/x86_64/init/main.c:1546) ? __pfx_kernel_init (kbuild/src/x86_64/init/main.c:1429) kernel_init (kbuild/src/x86_64/init/main.c:1439) ret_from_fork (kbuild/src/x86_64/arch/x86/kernel/process.c:145) ? __pfx_kernel_init (kbuild/src/x86_64/init/main.c:1429) ret_from_fork_asm (kbuild/src/x86_64/arch/x86/entry/entry_64.S:298) RIP: 0000:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0000:0000000000000000 EFLAGS: 00000000 ORIG_RAX: 0000000000000000 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> Closes: https://lore.kernel.org/oe-lkp/202307271656.447aa17e-oliver.sang@xxxxxxxxx Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> --- Hi, Looks like I didn't wait enough for kbuild :( Linus, do you prefer a pull request or to pick it right away? mm/memblock.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index c39b36378f5d..f9e61e565a53 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -374,10 +374,6 @@ void __init memblock_discard(void) kfree(memblock.reserved.regions); else memblock_free_late(addr, size); - /* Reset to prevent UAF from stray frees. */ - memblock.reserved.regions = memblock_reserved_init_regions; - memblock.reserved.cnt = 1; - memblock_remove_region(&memblock.reserved, 0); } if (memblock.memory.regions != memblock_memory_init_regions) { -- 2.39.2
