Re: [merged] kasan-fix-object-remain-in-offline-per-cpu-quarantine.patch removed from -mm tree

[Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>]

On Sat, 2020-12-12 at 22:05 -0800, akpm@linux-foundation.org wrote:
> The patch titled
>      Subject: kasan: fix object remaining in offline per-cpu quarantine
> has been removed from the -mm tree.  Its filename was
>      kasan-fix-object-remain-in-offline-per-cpu-quarantine.patch
> 
> This patch was dropped because it was merged into mainline or a subsystem tree
> 

Hi Andrew,

Sorry to bother.
This patch has dependency with two patches of Andrey's patch series as
below.
"kasan: rename get_alloc/free_info"
"kasan: sanitize objects when metadata doesnt fit"

If only merge this patch, it may cause some memory leak.
Could you please merge Andrey's whole patch series in mm-tree
into mainline together?

Thanks.

> ------------------------------------------------------
> From: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
> Subject: kasan: fix object remaining in offline per-cpu quarantine
> 
> We hit this issue in our internal test.  When enabling generic kasan, a
> kfree()'d object is put into per-cpu quarantine first.  If the cpu goes
> offline, object still remains in the per-cpu quarantine.  If we call
> kmem_cache_destroy() now, slub will report "Objects remaining" error.
> 
> [   74.982625] =============================================================================
> [   74.983380] BUG test_module_slab (Not tainted): Objects remaining in test_module_slab on __kmem_cache_shutdown()
> [   74.984145] -----------------------------------------------------------------------------
> [   74.984145]
> [   74.984883] Disabling lock debugging due to kernel taint
> [   74.985561] INFO: Slab 0x(____ptrval____) objects=34 used=1 fp=0x(____ptrval____) flags=0x2ffff00000010200
> [   74.986638] CPU: 3 PID: 176 Comm: cat Tainted: G    B             5.10.0-rc1-00007-g4525c8781ec0-dirty #10
> [   74.987262] Hardware name: linux,dummy-virt (DT)
> [   74.987606] Call trace:
> [   74.987924]  dump_backtrace+0x0/0x2b0
> [   74.988296]  show_stack+0x18/0x68
> [   74.988698]  dump_stack+0xfc/0x168
> [   74.989030]  slab_err+0xac/0xd4
> [   74.989346]  __kmem_cache_shutdown+0x1e4/0x3c8
> [   74.989779]  kmem_cache_destroy+0x68/0x130
> [   74.990176]  test_version_show+0x84/0xf0
> [   74.990679]  module_attr_show+0x40/0x60
> [   74.991218]  sysfs_kf_seq_show+0x128/0x1c0
> [   74.991656]  kernfs_seq_show+0xa0/0xb8
> [   74.992059]  seq_read+0x1f0/0x7e8
> [   74.992415]  kernfs_fop_read+0x70/0x338
> [   74.993051]  vfs_read+0xe4/0x250
> [   74.993498]  ksys_read+0xc8/0x180
> [   74.993825]  __arm64_sys_read+0x44/0x58
> [   74.994203]  el0_svc_common.constprop.0+0xac/0x228
> [   74.994708]  do_el0_svc+0x38/0xa0
> [   74.995088]  el0_sync_handler+0x170/0x178
> [   74.995497]  el0_sync+0x174/0x180
> [   74.996050] INFO: Object 0x(____ptrval____) @offset=15848
> [   74.996752] INFO: Allocated in test_version_show+0x98/0xf0 age=8188 cpu=6 pid=172
> [   75.000802]  stack_trace_save+0x9c/0xd0
> [   75.002420]  set_track+0x64/0xf0
> [   75.002770]  alloc_debug_processing+0x104/0x1a0
> [   75.003171]  ___slab_alloc+0x628/0x648
> [   75.004213]  __slab_alloc.isra.0+0x2c/0x58
> [   75.004757]  kmem_cache_alloc+0x560/0x588
> [   75.005376]  test_version_show+0x98/0xf0
> [   75.005756]  module_attr_show+0x40/0x60
> [   75.007035]  sysfs_kf_seq_show+0x128/0x1c0
> [   75.007433]  kernfs_seq_show+0xa0/0xb8
> [   75.007800]  seq_read+0x1f0/0x7e8
> [   75.008128]  kernfs_fop_read+0x70/0x338
> [   75.008507]  vfs_read+0xe4/0x250
> [   75.008990]  ksys_read+0xc8/0x180
> [   75.009462]  __arm64_sys_read+0x44/0x58
> [   75.010085]  el0_svc_common.constprop.0+0xac/0x228
> [   75.011006] kmem_cache_destroy test_module_slab: Slab cache still has objects
> 
> Register a cpu hotplug function to remove all objects in the offline
> per-cpu quarantine when cpu is going offline.  Set a per-cpu variable to
> indicate this cpu is offline.
> 
> [qiang.zhang@windriver.com: fix slab double free when cpu-hotplug]
>   Link: https://lkml.kernel.org/r/20201204102206.20237-1-qiang.zhang@windriver.com
> Link: https://lkml.kernel.org/r/1606895585-17382-2-git-send-email-Kuan-Ying.Lee@mediatek.com
> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
> Signed-off-by: Zqiang <qiang.zhang@windriver.com>
> Suggested-by: Dmitry Vyukov <dvyukov@google.com>
> Reported-by: Guangye Yang <guangye.yang@mediatek.com>
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Matthias Brugger <matthias.bgg@gmail.com>
> Cc: Nicholas Tang <nicholas.tang@mediatek.com>
> Cc: Miles Chen <miles.chen@mediatek.com>
> Cc: Qian Cai <qcai@redhat.com>
> Cc: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  mm/kasan/quarantine.c |   39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> --- a/mm/kasan/quarantine.c~kasan-fix-object-remain-in-offline-per-cpu-quarantine
> +++ a/mm/kasan/quarantine.c
> @@ -29,6 +29,7 @@
>  #include <linux/srcu.h>
>  #include <linux/string.h>
>  #include <linux/types.h>
> +#include <linux/cpuhotplug.h>
>  
>  #include "../slab.h"
>  #include "kasan.h"
> @@ -43,6 +44,7 @@ struct qlist_head {
>  	struct qlist_node *head;
>  	struct qlist_node *tail;
>  	size_t bytes;
> +	bool offline;
>  };
>  
>  #define QLIST_INIT { NULL, NULL, 0 }
> @@ -188,6 +190,10 @@ void quarantine_put(struct kasan_free_me
>  	local_irq_save(flags);
>  
>  	q = this_cpu_ptr(&cpu_quarantine);
> +	if (q->offline) {
> +		local_irq_restore(flags);
> +		return;
> +	}
>  	qlist_put(q, &info->quarantine_link, cache->size);
>  	if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
>  		qlist_move_all(q, &temp);
> @@ -328,3 +334,36 @@ void quarantine_remove_cache(struct kmem
>  
>  	synchronize_srcu(&remove_cache_srcu);
>  }
> +
> +static int kasan_cpu_online(unsigned int cpu)
> +{
> +	this_cpu_ptr(&cpu_quarantine)->offline = false;
> +	return 0;
> +}
> +
> +static int kasan_cpu_offline(unsigned int cpu)
> +{
> +	struct qlist_head *q;
> +
> +	q = this_cpu_ptr(&cpu_quarantine);
> +	/* Ensure the ordering between the writing to q->offline and
> +	 * qlist_free_all. Otherwise, cpu_quarantine may be corrupted
> +	 * by interrupt.
> +	 */
> +	WRITE_ONCE(q->offline, true);
> +	barrier();
> +	qlist_free_all(q, NULL);
> +	return 0;
> +}
> +
> +static int __init kasan_cpu_quarantine_init(void)
> +{
> +	int ret = 0;
> +
> +	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/kasan:online",
> +				kasan_cpu_online, kasan_cpu_offline);
> +	if (ret < 0)
> +		pr_err("kasan cpu quarantine register failed [%d]\n", ret);
> +	return ret;
> +}
> +late_initcall(kasan_cpu_quarantine_init);
> _
> 
> Patches currently in -mm which might be from Kuan-Ying.Lee@mediatek.com are
> 
>