On Mon, 2020-12-07 at 10:06 +0800, Kuan-Ying Lee wrote: > On Sat, 2020-12-05 at 17:09 -0800, Andrew Morton wrote: > > On Sun, 6 Dec 2020 00:17:15 +0800 Kuan-Ying Lee > > <kuan-ying....@mediatek.com> wrote: > > > > > On Fri, 2020-12-04 at 17:25 -0800, Andrew Morton wrote: > > > > On Fri, 4 Dec 2020 20:01:35 +0800 Kuan-Ying Lee > > > > <kuan-ying....@mediatek.com> wrote: > > > > > > > > > > diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c > > > > > > index d98b516f372f..55783125a767 100644 > > > > > > --- a/mm/kasan/quarantine.c > > > > > > +++ b/mm/kasan/quarantine.c > > > > > > @@ -194,7 +194,6 @@ bool quarantine_put(struct kmem_cache *cache, > > > > > > void *object) > > > > > > > > > > > > q = this_cpu_ptr(&cpu_quarantine); > > > > > > if (q->offline) { > > > > > > - qlink_free(&meta->quarantine_link, cache); > > > > > > local_irq_restore(flags); > > > > > > return false; > > > > > > Hi Andrew, > > > > > > Return false will cause slab allocator to free the object. > > > Thus, we do not need to qlink_free here to free object twice. > > > > > > The return value is introduced from Andrey's patch. > > > "kasan: sanitize objects when metadata doesn't fit" > > > > > > > > > > > > } > > > > > > > > > > Hi Qiang, > > > > > > > > > > Thanks for fixing this. > > > > > Due to that issue, my commit has been removed by Stephen from > > > > > linux-next. > > > > > > > > > > > > > > > Hi Stephen, Andrew, > > > > > > > > > > Should I directly upload the v4 or Stephen can pick the commit which > > > > > has been removed back to the linux-next. > > > > > > > > I took care of it. Restored the original patch and added this one as a > > > > -fix. > > > > > > Thanks for taking care of it. > > > > > > I think there are some problem in the patch you just restored. > > > I saw the restored patch is not based on Andrey's patch and Stephen's > > > fix conflict patch. > > > > > > But the issue Qiang fixed need to be based on the Andrey's patch and > > > Stephen's fix conflict patch. > > > "kasan: sanitize objects when metadata doesn't fit" > > > "kasan-rename-get_alloc-free_info-fix" > > > > > > If the restored patch is not based on that, it may cause some problems > > > and conflicts. > > > > > > I think I can prepare a patch v4 based on Andrey's patch, fix the > > > conflict and include the Qiang's modification. > > > > I'm not sure what you mean here. When appying this fix, yes, I had to > > replace "meta" with "info", of course. > > > > So the combined patch, which I'd like to send to Linus next week is as > > below. Is there something wrong with it? > > > > Is this combined patch based on Andrey's patch? > > If yes, Andrey's patch not only change the "info" to "meta" but also > introduce the return value. > I think we need to add return value or it will build error. >
Hi Andrew, Sorry to bother. Thanks for fixing my patch. But it still has some problem. I know you are busy. I can fix that by myself. I will upload the patch v4 to fix the conflicts and build errors and include the Qiang's patch. Thanks. Kuan-Ying > > > > From: Kuan-Ying Lee <kuan-ying....@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.zh...@windriver.com: fix slab double free when cpu-hotplug] > > Link: > > https://lkml.kernel.org/r/20201204102206.20237-1-qiang.zh...@windriver.com > > Link: > > https://lkml.kernel.org/r/1606895585-17382-2-git-send-email-kuan-ying....@mediatek.com > > Signed-off-by: Kuan-Ying Lee <kuan-ying....@mediatek.com> > > Signed-off-by: Zqiang <qiang.zh...@windriver.com> > > Suggested-by: Dmitry Vyukov <dvyu...@google.com> > > Reported-by: Guangye Yang <guangye.y...@mediatek.com> > > Reviewed-by: Dmitry Vyukov <dvyu...@google.com> > > Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> > > Cc: Alexander Potapenko <gli...@google.com> > > Cc: Matthias Brugger <matthias....@gmail.com> > > Cc: Nicholas Tang <nicholas.t...@mediatek.com> > > Cc: Miles Chen <miles.c...@mediatek.com> > > Cc: Qian Cai <q...@redhat.com> > > Cc: Stephen Rothwell <s...@canb.auug.org.au> > > Signed-off-by: Andrew Morton <a...@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 > > Andrey's patch changes the return value from "void" to "bool". > We need to replace void with bool. > > > local_irq_save(flags); > > > > q = this_cpu_ptr(&cpu_quarantine); > > + if (q->offline) { > > + local_irq_restore(flags); > > + return; > > I think we need to return false here. Otherwise, it will lack return > value and cause build error. > > > + } > > qlist_put(q, &info->quarantine_link, cache->size); > > This "info" may cause conflict because Andrey's patch has already > changed it to "meta". > > Thanks. > Kuan-Ying > > > 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); > > _ > > >