From: Hyeonggon Yoo 42.hyeyoo@gmail.com
commit 2839b0999c20c9f6bf353849c69370e121e2fa1a upstream.
When kfence fails to initialize kfence pool, it frees the pool. But it does not reset memcg_data and PG_slab flag.
Below is a BUG because of this. Let's fix it by resetting memcg_data and PG_slab flag before free.
[ 0.089149] BUG: Bad page state in process swapper/0 pfn:3d8e06 [ 0.089149] page:ffffea46cf638180 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3d8e06 [ 0.089150] memcg:ffffffff94a475d1 [ 0.089150] flags: 0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff) [ 0.089151] raw: 0017ffffc0000200 ffffea46cf638188 ffffea46cf638188 0000000000000000 [ 0.089152] raw: 0000000000000000 0000000000000000 00000000ffffffff ffffffff94a475d1 [ 0.089152] page dumped because: page still charged to cgroup [ 0.089153] Modules linked in: [ 0.089153] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G B W 5.18.0-rc1+ #965 [ 0.089154] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 0.089154] Call Trace: [ 0.089155] <TASK> [ 0.089155] dump_stack_lvl+0x49/0x5f [ 0.089157] dump_stack+0x10/0x12 [ 0.089158] bad_page.cold+0x63/0x94 [ 0.089159] check_free_page_bad+0x66/0x70 [ 0.089160] __free_pages_ok+0x423/0x530 [ 0.089161] __free_pages_core+0x8e/0xa0 [ 0.089162] memblock_free_pages+0x10/0x12 [ 0.089164] memblock_free_late+0x8f/0xb9 [ 0.089165] kfence_init+0x68/0x92 [ 0.089166] start_kernel+0x789/0x992 [ 0.089167] x86_64_start_reservations+0x24/0x26 [ 0.089168] x86_64_start_kernel+0xa9/0xaf [ 0.089170] secondary_startup_64_no_verify+0xd5/0xdb [ 0.089171] </TASK>
Link: https://lkml.kernel.org/r/YnPG3pQrqfcgOlVa@hyeyoo Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Fixes: 8f0b36497303 ("mm: kfence: fix objcgs vector allocation") Signed-off-by: Hyeonggon Yoo 42.hyeyoo@gmail.com Reviewed-by: Marco Elver elver@google.com Reviewed-by: Muchun Song songmuchun@bytedance.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/kfence/core.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
--- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -515,6 +515,7 @@ static bool __init kfence_init_pool(void { unsigned long addr = (unsigned long)__kfence_pool; struct page *pages; + char *p; int i;
if (!__kfence_pool) @@ -598,6 +599,16 @@ err: * fails for the first page, and therefore expect addr==__kfence_pool in * most failure cases. */ + for (p = (char *)addr; p < __kfence_pool + KFENCE_POOL_SIZE; p += PAGE_SIZE) { + struct slab *slab = virt_to_slab(p); + + if (!slab) + continue; +#ifdef CONFIG_MEMCG + slab->memcg_data = 0; +#endif + __folio_clear_slab(slab_folio(slab)); + } memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)__kfence_pool)); __kfence_pool = NULL; return false;