Re: [PATCH v2] lib: stackdepot: Add support to configure STACK_HASH_SIZE

From: Andrey Konovalov
Date: Thu Dec 03 2020 - 11:16:55 EST

On Thu, Dec 3, 2020 at 5:04 PM Qian Cai <qcai@xxxxxxxxxx> wrote:
>
> On Thu, 2020-11-26 at 10:13 +0530, vjitta@xxxxxxxxxxxxxx wrote:
> > From: Yogesh Lal <ylal@xxxxxxxxxxxxxx>
> >
> > Add a kernel parameter stack_hash_order to configure STACK_HASH_SIZE.
> >
> > Aim is to have configurable value for STACK_HASH_SIZE, so that one
> > can configure it depending on usecase there by reducing the static
> > memory overhead.
> >
> > One example is of Page Owner, default value of STACK_HASH_SIZE lead
> > stack depot to consume 8MB of static memory. Making it configurable
> > and use lower value helps to enable features like CONFIG_PAGE_OWNER
> > without any significant overhead.
> >
> > Suggested-by: Minchan Kim <minchan@xxxxxxxxxx>
> > Signed-off-by: Yogesh Lal <ylal@xxxxxxxxxxxxxx>
> > Signed-off-by: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx>
>
> Reverting this commit on today's linux-next fixed boot crash with KASAN.
>
> .config:
> https://cailca.coding.net/public/linux/mm/git/files/master/x86.config
> https://cailca.coding.net/public/linux/mm/git/files/master/arm64.config
>
>
> [ 5.135848][ T0] random: get_random_u64 called from __kmem_cache_create+0x2e/0x490 with crng_init=0
> [ 5.135909][ T0] BUG: unable to handle page fault for address: 00000000002ac6d0
> [ 5.152733][ T0] #PF: supervisor read access in kernel mode
> [ 5.158585][ T0] #PF: error_code(0x0000) - not-present page
> [ 5.164438][ T0] PGD 0 P4D 0
> [ 5.167670][ T0] Oops: 0000 [#1] SMP KASAN NOPTI
> [ 5.172566][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0-rc6-next-20201203+ #3
> [ 5.180685][ T0] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
> [ 5.189950][ T0] RIP: 0010:stack_depot_save+0xf4/0x460
> stack_depot_save at lib/stackdepot.c:272
> [ 5.195362][ T0] Code: 00 00 83 ff 01 0f 84 b3 00 00 00 8b 0d 35 67 39 08 b8 01 00 00 00 48 d3 e0 48 8b 0d 46 9c 27 11 48 83 e8 01 21 d8 4c 8d 34 c1 <4d> 8b 2e 4d 85 ed 0f 84 ca 00 00 00 41 8d 74 24 ff 48 c1 e6 03 eb
> [ 5.214927][ T0] RSP: 0000:ffffffff99007c18 EFLAGS: 00010002
> [ 5.220865][ T0] RAX: 00000000000558da RBX: 00000000caa558da RCX: 0000000000000000
> [ 5.228726][ T0] RDX: 0000000000000cc0 RSI: 00000000e11e461a RDI: 0000000000000001
> [ 5.236590][ T0] RBP: ffffffff99007c68 R08: 000000002ff39dab R09: 0000000000000007
> [ 5.244450][ T0] R10: ffffffff99007b60 R11: 0000000000000005 R12: 0000000000000008
> [ 5.252313][ T0] R13: ffff8881000400b7 R14: 00000000002ac6d0 R15: 0000000000000078
> [ 5.260173][ T0] FS: 0000000000000000(0000) GS:ffff88881e800000(0000) knlGS:0000000000000000
> [ 5.268996][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 5.275674][ T0] CR2: 00000000002ac6d0 CR3: 0000000cc8814000 CR4: 00000000000406b0
> [ 5.283534][ T0] Call Trace:
> [ 5.286687][ T0] kasan_save_stack+0x2f/0x40
> [ 5.291225][ T0] ? kasan_save_stack+0x19/0x40
> [ 5.295939][ T0] ? ____kasan_kmalloc.constprop.8+0x85/0xa0
> [ 5.301793][ T0] ? __kmem_cache_create+0x26a/0x490
> [ 5.306950][ T0] ? create_boot_cache+0x75/0x98
> [ 5.311751][ T0] ? kmem_cache_init+0x42/0x146
> [ 5.316471][ T0] ? mm_init+0x64/0x87
> [ 5.320399][ T0] ? start_kernel+0x14c/0x3a7
> [ 5.324945][ T0] ? secondary_startup_64_no_verify+0xc2/0xcb
> [ 5.330885][ T0] ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
> [ 5.336733][ T0] ? lockdep_hardirqs_on_prepare+0x3d0/0x3d0
> [ 5.342590][ T0] ? __isolate_free_page+0x540/0x540
> [ 5.347742][ T0] ? find_held_lock+0x33/0x1c0
> [ 5.352371][ T0] ? __alloc_pages_nodemask+0x534/0x700
> [ 5.357784][ T0] ? __alloc_pages_slowpath.constprop.110+0x20f0/0x20f0
> [ 5.364600][ T0] ? __kasan_init_slab_obj+0x20/0x30
> [ 5.369753][ T0] ? unpoison_range+0xf/0x30
> [ 5.374207][ T0] ____kasan_kmalloc.constprop.8+0x85/0xa0
> kasan_set_track at mm/kasan/common.c:47
> (inlined by) set_alloc_info at mm/kasan/common.c:405
> (inlined by) ____kasan_kmalloc at mm/kasan/common.c:436
> [ 5.379886][ T0] __kmem_cache_create+0x26a/0x490
> early_kmem_cache_node_alloc at mm/slub.c:3566
> (inlined by) init_kmem_cache_nodes at mm/slub.c:3606
> (inlined by) kmem_cache_open at mm/slub.c:3858
> (inlined by) __kmem_cache_create at mm/slub.c:4468
> [ 5.384864][ T0] create_boot_cache+0x75/0x98
> create_boot_cache at mm/slab_common.c:568
> [ 5.389493][ T0] kmem_cache_init+0x42/0x146
> [ 5.394035][ T0] mm_init+0x64/0x87
> [ 5.397791][ T0] start_kernel+0x14c/0x3a7
> [ 5.402159][ T0] ? copy_bootdata+0x19/0x47
> [ 5.406615][ T0] secondary_startup_64_no_verify+0xc2/0xcb
> [ 5.412380][ T0] Modules linked in:
> [ 5.416136][ T0] CR2: 00000000002ac6d0
> [ 5.420158][ T0] ---[ end trace c97cf41616dddbe6 ]---
> [ 5.425483][ T0] RIP: 0010:stack_depot_save+0xf4/0x460
> [ 5.430898][ T0] Code: 00 00 83 ff 01 0f 84 b3 00 00 00 8b 0d 35 67 39 08 b8 01 00 00 00 48 d3 e0 48 8b 0d 46 9c 27 11 48 83 e8 01 21 d8 4c 8d 34 c1 <4d> 8b 2e 4d 85 ed 0f 84 ca 00 00 00 41 8d 74 24 ff 48 c1 e6 03 eb
> [ 5.450464][ T0] RSP: 0000:ffffffff99007c18 EFLAGS: 00010002
> [ 5.456403][ T0] RAX: 00000000000558da RBX: 00000000caa558da RCX: 0000000000000000
> [ 5.464264][ T0] RDX: 0000000000000cc0 RSI: 00000000e11e461a RDI: 0000000000000001
> [ 5.472127][ T0] RBP: ffffffff99007c68 R08: 000000002ff39dab R09: 0000000000000007
> [ 5.479988][ T0] R10: ffffffff99007b60 R11: 0000000000000005 R12: 0000000000000008
> [ 5.487849][ T0] R13: ffff8881000400b7 R14: 00000000002ac6d0 R15: 0000000000000078
> [ 5.495712][ T0] FS: 0000000000000000(0000) GS:ffff88881e800000(0000) knlGS:0000000000000000
> [ 5.504534][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 5.510998][ T0] CR2: 00000000002ac6d0 CR3: 0000000cc8814000 CR4: 00000000000406b0
> [ 5.518860][ T0] Kernel panic - not syncing: Fatal exception
> [ 5.524915][ T0] ---[ end Kernel panic - not syncing: Fatal exception ]---
>

Vincenzo, Catalin, looks like this is the cause of the crash you
observed. Reverting this commit from next-20201203 fixes KASAN for me.

Thanks for the report Qian!

> > ---
> > lib/stackdepot.c | 27 ++++++++++++++++++++++-----
> > 1 file changed, 22 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/stackdepot.c b/lib/stackdepot.c
> > index 81c69c0..ce53598 100644
> > --- a/lib/stackdepot.c
> > +++ b/lib/stackdepot.c
> > @@ -141,14 +141,31 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
> > return stack;
> > }
> >
> > -#define STACK_HASH_ORDER 20
> > -#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER)
> > +static unsigned int stack_hash_order = 20;
> > +#define STACK_HASH_SIZE (1L << stack_hash_order)
> > #define STACK_HASH_MASK (STACK_HASH_SIZE - 1)
> > #define STACK_HASH_SEED 0x9747b28c
> >
> > -static struct stack_record *stack_table[STACK_HASH_SIZE] = {
> > - [0 ... STACK_HASH_SIZE - 1] = NULL
> > -};
> > +static struct stack_record **stack_table;
> > +
> > +static int __init setup_stack_hash_order(char *str)
> > +{
> > + kstrtouint(str, 0, &stack_hash_order);
> > + return 0;
> > +}
> > +early_param("stack_hash_order", setup_stack_hash_order);
> > +
> > +static int __init init_stackdepot(void)
> > +{
> > + int i;
> > +
> > + stack_table = kvmalloc(sizeof(struct stack_record *) * STACK_HASH_SIZE, GFP_KERNEL);
> > + for (i = 0; i < STACK_HASH_SIZE; i++)
> > + stack_table[i] = NULL;
> > + return 0;
> > +}
> > +
> > +early_initcall(init_stackdepot);
> >
> > /* Calculate hash for a stack */
> > static inline u32 hash_stack(unsigned long *entries, unsigned int size)
>
> --
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