On Tue, Mar 16, 2021 at 04:42PM +0000, Luis Henriques wrote: > Hi! > > This is probably a known issue, but just in case: looks like it's not > possible to use kmemleak when kfence is enabled: Thanks for spotting this. > [ 0.272136] kmemleak: Cannot insert 0xffff888236e02f00 into the object search tree (overlaps existing) > [ 0.272136] CPU: 0 PID: 8 Comm: kthreadd Not tainted 5.12.0-rc3+ #92 > [ 0.272136] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 > [ 0.272136] Call Trace: > [ 0.272136] dump_stack+0x6d/0x89 > [ 0.272136] create_object.isra.0.cold+0x40/0x62 > [ 0.272136] ? process_one_work+0x5a0/0x5a0 > [ 0.272136] ? process_one_work+0x5a0/0x5a0 > [ 0.272136] kmem_cache_alloc_trace+0x110/0x2f0 > [ 0.272136] ? process_one_work+0x5a0/0x5a0 > [ 0.272136] kthread+0x3f/0x150 > [ 0.272136] ? lockdep_hardirqs_on_prepare+0xd4/0x170 > [ 0.272136] ? __kthread_bind_mask+0x60/0x60 > [ 0.272136] ret_from_fork+0x22/0x30 > [ 0.272136] kmemleak: Kernel memory leak detector disabled > [ 0.272136] kmemleak: Object 0xffff888236e00000 (size 2097152): > [ 0.272136] kmemleak: comm "swapper", pid 0, jiffies 4294892296 > [ 0.272136] kmemleak: min_count = 0 > [ 0.272136] kmemleak: count = 0 > [ 0.272136] kmemleak: flags = 0x1 > [ 0.272136] kmemleak: checksum = 0 > [ 0.272136] kmemleak: backtrace: > [ 0.272136] memblock_alloc_internal+0x6d/0xb0 > [ 0.272136] memblock_alloc_try_nid+0x6c/0x8a > [ 0.272136] kfence_alloc_pool+0x26/0x3f > [ 0.272136] start_kernel+0x242/0x548 > [ 0.272136] secondary_startup_64_no_verify+0xb0/0xbb > > I've tried the hack below but it didn't really helped. Obviously I don't > really understand what's going on ;-) But I think the reason for this > patch not working as (I) expected is because kfence is initialised > *before* kmemleak. > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > index 3b8ec938470a..b4ffd7695268 100644 > --- a/mm/kfence/core.c > +++ b/mm/kfence/core.c > @@ -631,6 +631,9 @@ void __init kfence_alloc_pool(void) > > if (!__kfence_pool) > pr_err("failed to allocate pool\n"); > + kmemleak_no_scan(__kfence_pool); > } Can you try the below patch? Thanks, -- Marco ------ >8 ------ diff --git a/mm/kfence/core.c b/mm/kfence/core.c index f7106f28443d..5891019721f6 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -12,6 +12,7 @@ #include <linux/debugfs.h> #include <linux/kcsan-checks.h> #include <linux/kfence.h> +#include <linux/kmemleak.h> #include <linux/list.h> #include <linux/lockdep.h> #include <linux/memblock.h> @@ -481,6 +482,13 @@ static bool __init kfence_init_pool(void) addr += 2 * PAGE_SIZE; } + /* + * The pool is live and will never be deallocated from this point on; + * tell kmemleak this is now free memory, so that later allocations can + * correctly be tracked. + */ + kmemleak_free_part_phys(__pa(__kfence_pool), KFENCE_POOL_SIZE); + return true; err: