Re: [PATCH v1] lib/stackdepot: limit nr_entries size

From: Dmitry Vyukov
Date: Tue Apr 18 2023 - 02:54:59 EST

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On Tue, 18 Apr 2023 at 08:10, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>
> On Tue, 18 Apr 2023 at 06:10, hoyoung seo <hy50.seo@xxxxxxxxxxx> wrote:
> >
> > > -----Original Message-----
> > > From: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> > > Sent: Monday, April 17, 2023 3:20 PM
> > > To: SEO HOYOUNG <hy50.seo@xxxxxxxxxxx>
> > > Cc: andreyknvl@xxxxxxxxx; osalvador@xxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx;
> > > linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; mhocko@xxxxxxxx;
> > > vbabka@xxxxxxx; edumazet@xxxxxxxxxx; longman@xxxxxxxxxx; surenb@xxxxxxxxxx;
> > > elver@xxxxxxxxxx; glider@xxxxxxxxxx
> > > Subject: Re: [PATCH v1] lib/stackdepot: limit nr_entries size
> > >
> > > On Mon, 17 Apr 2023 at 07:16, SEO HOYOUNG <hy50.seo@xxxxxxxxxxx> wrote:
> > > >
> > > > While using the MCQ feature of UFS, dump stack was detected very deeply.
> > > > If this continues to happen, depot_alloc_stack() will continue to
> > > > exceed STACK_ALLOC_SIZE and STACK_ALLOC_MAX_SLABS, eventually
> > > > resulting in the warning "Stack depot reached limit capacity".
> > > >
> > > > So want to limit the size of entries stored in it.
> > > > 25 is a test value, and we found that in a normal case, the depth of
> > > > the stack does not exceed 25.
> > > >
> > > > [ 2479.383395]I[0:launcher-loader: 1719] Stack depot reached limit
> > > > capacity [ 2479.383538]I[0:launcher-loader: 1719] WARNING: CPU: 0 PID:
> > > > 1719 at lib/stackdepot.c:129 __stack_depot_save+0x464/0x46c [
> > > > 2479.385693]I[0:launcher-loader: 1719] pstate: 624000c5 (nZCv daIF
> > > > +PAN -UAO +TCO -DIT -SSBS BTYPE=--) [ 2479.385724]I[0:launcher-loader:
> > > > 1719] pc : __stack_depot_save+0x464/0x46c [
> > > > 2479.385751]I[0:launcher-loader: 1719] lr :
> > > > __stack_depot_save+0x460/0x46c [ 2479.385774]I[0:launcher-loader:
> > > > 1719] sp : ffffffc0080073c0 [ 2479.385793]I[0:launcher-loader: 1719]
> > > > x29: ffffffc0080073e0 x28: ffffffd00b78a000 x27: 0000000000000000 [
> > > > 2479.385839]I[0:launcher-loader: 1719] x26: 000000000004d1dd x25:
> > > > ffffff891474f000 x24: 00000000ca64d1dd [
> > > > 2479.385882]I[0:launcher-loader: 1719] x23: 0000000000000200 x22:
> > > > 0000000000000220 x21: 0000000000000040 [
> > > > 2479.385925]I[0:launcher-loader: 1719] x20: ffffffc008007440 x19:
> > > > 0000000000000000 x18: 0000000000000000 [
> > > > 2479.385969]I[0:launcher-loader: 1719] x17: 2065726568207475 x16:
> > > 000000000000005e x15: 2d2d2d2d2d2d2d20 [ 2479.386013]I[0:launcher-loader:
> > > 1719] x14: 5d39313731203a72 x13: 00000000002f6b30 x12: 00000000002f6af8
> > > [ 2479.386057]I[0:launcher-loader: 1719] x11: 00000000ffffffff x10:
> > > ffffffb90aacf000 x9 : e8a74a6c16008800 [ 2479.386101]I[0:launcher-loader:
> > > 1719] x8 : e8a74a6c16008800 x7 : 00000000002f6b30 x6 : 00000000002f6af8
> > > [ 2479.386145]I[0:launcher-loader: 1719] x5 : ffffffc0080070c8 x4 :
> > > ffffffd00b192380 x3 : ffffffd0092b313c [ 2479.386189]I[0:launcher-loader:
> > > 1719] x2 : 0000000000000001 x1 : 0000000000000004 x0 : 0000000000000022
> > > [ 2479.386231]I[0:launcher-loader: 1719] Call trace:
> > > > [ 2479.386248]I[0:launcher-loader: 1719]
> > > > __stack_depot_save+0x464/0x46c [ 2479.386273]I[0:launcher-loader:
> > > > 1719] kasan_save_stack+0x58/0x70 [ 2479.386303]I[0:launcher-loader:
> > > > 1719] save_stack_info+0x34/0x138 [ 2479.386331]I[0:launcher-loader:
> > > > 1719] kasan_save_free_info+0x18/0x24 [
> > > > 2479.386358]I[0:launcher-loader: 1719]
> > > > ____kasan_slab_free+0x16c/0x170 [ 2479.386385]I[0:launcher-loader:
> > > > 1719] __kasan_slab_free+0x10/0x20 [ 2479.386410]I[0:launcher-loader:
> > > > 1719] kmem_cache_free+0x238/0x53c [ 2479.386435]I[0:launcher-loader:
> > > > 1719] mempool_free_slab+0x1c/0x28 [ 2479.386460]I[0:launcher-loader:
> > > > 1719] mempool_free+0x7c/0x1a0 [ 2479.386484]I[0:launcher-loader:
> > > > 1719] bvec_free+0x34/0x80 [ 2479.386514]I[0:launcher-loader: 1719]
> > > > bio_free+0x60/0x98 [ 2479.386540]I[0:launcher-loader: 1719]
> > > > bio_put+0x50/0x21c [ 2479.386567]I[0:launcher-loader: 1719]
> > > > f2fs_write_end_io+0x4ac/0x4d0 [ 2479.386594]I[0:launcher-loader: 1719]
> > > > bio_endio+0x2dc/0x300 [ 2479.386622]I[0:launcher-loader: 1719]
> > > > __dm_io_complete+0x324/0x37c [ 2479.386650]I[0:launcher-loader: 1719]
> > > > dm_io_dec_pending+0x60/0xa4 [ 2479.386676]I[0:launcher-loader: 1719]
> > > > clone_endio+0xf8/0x2f0 [ 2479.386700]I[0:launcher-loader: 1719]
> > > > bio_endio+0x2dc/0x300 [ 2479.386727]I[0:launcher-loader: 1719]
> > > > blk_update_request+0x258/0x63c [ 2479.386754]I[0:launcher-loader:
> > > > 1719] scsi_end_request+0x50/0x304 [ 2479.386782]I[0:launcher-loader:
> > > > 1719] scsi_io_completion+0x88/0x160 [
> > > > 2479.386808]I[0:launcher-loader: 1719]
> > > > scsi_finish_command+0x17c/0x194 [ 2479.386833]I[0:launcher-loader:
> > > > 1719] scsi_complete+0xcc/0x158 [ 2479.386859]I[0:launcher-loader:
> > > > 1719] blk_mq_complete_request+0x4c/0x5c [
> > > > 2479.386885]I[0:launcher-loader: 1719] scsi_done_internal+0xf4/0x1e0
> > > > [ 2479.386910]I[0:launcher-loader: 1719] scsi_done+0x14/0x20 [
> > > > 2479.386935]I[0:launcher-loader: 1719]
> > > > ufshcd_compl_one_cqe+0x578/0x71c [ 2479.386963]I[0:launcher-loader:
> > > > 1719] ufshcd_mcq_poll_cqe_nolock+0xc8/0x150
> > > > [ 2479.386991]I[0:launcher-loader: 1719] ufshcd_intr+0x868/0xc0c [
> > > > 2479.387017]I[0:launcher-loader: 1719]
> > > > __handle_irq_event_percpu+0xd0/0x348
> > > > [ 2479.387044]I[0:launcher-loader: 1719]
> > > > handle_irq_event_percpu+0x24/0x74 [ 2479.387068]I[0:launcher-loader:
> > > > 1719] handle_irq_event+0x74/0xe0 [ 2479.387091]I[0:launcher-loader:
> > > > 1719] handle_fasteoi_irq+0x174/0x240 [
> > > > 2479.387118]I[0:launcher-loader: 1719] handle_irq_desc+0x7c/0x2c0 [
> > > > 2479.387147]I[0:launcher-loader: 1719]
> > > > generic_handle_domain_irq+0x1c/0x28
> > > > [ 2479.387174]I[0:launcher-loader: 1719] gic_handle_irq+0x64/0x158 [
> > > > 2479.387204]I[0:launcher-loader: 1719] call_on_irq_stack+0x2c/0x54 [
> > > > 2479.387231]I[0:launcher-loader: 1719] do_interrupt_handler+0x70/0xa0
> > > > [ 2479.387258]I[0:launcher-loader: 1719] el1_interrupt+0x34/0x68 [
> > > > 2479.387283]I[0:launcher-loader: 1719] el1h_64_irq_handler+0x18/0x24
> > > > [ 2479.387308]I[0:launcher-loader: 1719] el1h_64_irq+0x68/0x6c [
> > > > 2479.387332]I[0:launcher-loader: 1719]
> > > > blk_attempt_bio_merge+0x8/0x170 [ 2479.387356]I[0:launcher-loader:
> > > > 1719] blk_mq_attempt_bio_merge+0x78/0x98
> > > > [ 2479.387383]I[0:launcher-loader: 1719]
> > > > blk_mq_submit_bio+0x324/0xa40 [ 2479.387409]I[0:launcher-loader: 1719]
> > > > __submit_bio+0x104/0x138 [ 2479.387436]I[0:launcher-loader: 1719]
> > > > submit_bio_noacct_nocheck+0x1d0/0x4a0
> > > > [ 2479.387462]I[0:launcher-loader: 1719]
> > > > submit_bio_noacct+0x618/0x804 [ 2479.387487]I[0:launcher-loader: 1719]
> > > > submit_bio+0x164/0x180 [ 2479.387511]I[0:launcher-loader: 1719]
> > > > f2fs_submit_read_bio+0xe4/0x1c4 [ 2479.387537]I[0:launcher-loader:
> > > > 1719] f2fs_mpage_readpages+0x888/0xa4c [
> > > > 2479.387563]I[0:launcher-loader: 1719] f2fs_readahead+0xd4/0x19c [
> > > > 2479.387587]I[0:launcher-loader: 1719] read_pages+0xb0/0x4ac [
> > > > 2479.387614]I[0:launcher-loader: 1719]
> > > > page_cache_ra_unbounded+0x238/0x288
> > > > [ 2479.387642]I[0:launcher-loader: 1719] do_page_cache_ra+0x60/0x6c [
> > > > 2479.387669]I[0:launcher-loader: 1719]
> > > > page_cache_ra_order+0x318/0x364 [ 2479.387695]I[0:launcher-loader:
> > > > 1719] ondemand_readahead+0x30c/0x3d8 [
> > > > 2479.387722]I[0:launcher-loader: 1719] page_cache_sync_ra+0xb4/0xc8 [
> > > > 2479.387749]I[0:launcher-loader: 1719] filemap_read+0x268/0xd24 [
> > > > 2479.387777]I[0:launcher-loader: 1719]
> > > > f2fs_file_read_iter+0x1a0/0x62c [ 2479.387806]I[0:launcher-loader:
> > > > 1719] vfs_read+0x258/0x34c [ 2479.387831]I[0:launcher-loader: 1719]
> > > > ksys_pread64+0x8c/0xd0 [ 2479.387857]I[0:launcher-loader: 1719]
> > > > __arm64_sys_pread64+0x48/0x54 [ 2479.387881]I[0:launcher-loader: 1719]
> > > > invoke_syscall+0x58/0x158 [ 2479.387909]I[0:launcher-loader: 1719]
> > > > el0_svc_common+0xf0/0x134 [ 2479.387935]I[0:launcher-loader: 1719]
> > > > do_el0_svc+0x44/0x114 [ 2479.387961]I[0:launcher-loader: 1719]
> > > > el0_svc+0x2c/0x80 [ 2479.387985]I[0:launcher-loader: 1719]
> > > > el0t_64_sync_handler+0x48/0x114 [ 2479.388010]I[0:launcher-loader: 1719]
> > > el0t_64_sync+0x190/0x194 [ 2479.388038]I[0:launcher-loader: 1719] Kernel
> > > panic - not syncing: kernel: panic_on_warn set ...
> > > >
> > > > Signed-off-by: SEO HOYOUNG <hy50.seo@xxxxxxxxxxx>
> > > > ---
> > > > lib/stackdepot.c | 3 ++-
> > > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c index
> > > > 2f5aa851834e..f158729598a6 100644
> > > > --- a/lib/stackdepot.c
> > > > +++ b/lib/stackdepot.c
> > > > @@ -43,6 +43,7 @@
> > > > #define DEPOT_MAX_POOLS \
> > > > (((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \
> > > > (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP)
> > > > +#define DEPO_MAX_DEPTH 25
> > > >
> > > > /* Compact structure that stores a reference to a stack. */ union
> > > > handle_parts { @@ -375,7 +376,7 @@ depot_stack_handle_t
> > > > __stack_depot_save(unsigned long *entries,
> > > > * filter_irq_stacks() to simplify all callers' use of stack depot.
> > > > */
> > > > nr_entries = filter_irq_stacks(entries, nr_entries);
> > > > -
> > > > + nr_entries = nr_entries > DEPO_MAX_DEPTH ? DEPO_MAX_DEPTH :
> > > > + nr_entries;
> > > > if (unlikely(nr_entries == 0) || stack_depot_disabled)
> > > > goto fast_exit;
> > >
> > > Hi SEO,
> > >
> > > The stack overflow errors are related to total number of stacks rather
> > > than size of a single stack.
> > >
> > > filter_irq_stacks() is somehow not working in your case. It's supposed to
> > > strip stacks somewhere around el1_interrupt (on interrupt entry), but it's
> > > failing to do it.
> > > As a result you are getting an effectively infinite amount of random
> > > stacks saved.
> > >
> > > You need to debug why filter_irq_stacks() is failing in your case and fix
> > > that instead.
> >
> > Hi Vyukov.
> >
> > Thanks your reply.
> > As you say, the filter_irq_stacks() doesn't seem to be work correctly.
> > I checked by print a symbol name, and it looks like the filter itself is wrong.
> > __irqentry_text_start -> _stext+0x0/0x66c
> > __irqentry_text_end -> _stext+0x0/0x66c
> >
> > __softirqentry_text_start -> _stext+0x0/0x66c
> > __softirqentry_text_end -> __softirqentry_text_end+0x0/0x4
> > Do you have the symbol name you were originally expecting?
> >
> > The problem seems to be caused by not riding the call stack defined
> > by __irqentry_text_start, __irqentry_text_end when h/w irq occurs in our driver.
> > If you can tell us the call stack names defined by __irqentry_text_start, __irqentry_text_end,
> > it will help us to solve the problem.
>
> These __irqentry_text_start/end markers should contain all irq entry functions.
>
> For example, for a random x86 kernel I see:
>
> $ nm -ngS vmlinux | grep -C 3 irqentry_text
> ffffffff8aaeffc0 00000000000008d9 T __do_softirq
> ffffffff8aaeffc0 T __kprobes_text_end
> ffffffff8aaeffc0 T __kprobes_text_start
> ffffffff8aaeffc0 T __softirqentry_text_start
> ffffffff8aaf0899 T __softirqentry_text_end
> ffffffff8aaf08a0 0000000000000008 T __SCT__tp_func_initcall_level
> ffffffff8aaf08a0 T __static_call_text_start
> ffffffff8aaf08a8 0000000000000008 T __SCT__tp_func_initcall_start
> --
> ffffffff8ac0013f T entry_SYSRETQ_end
> ffffffff8ac00140 0000000000000049 T xen_error_entry
> ffffffff8ac00190 0000000000000cc0 T irq_entries_start
> ffffffff8ac00190 T __irqentry_text_start
> ffffffff8ac00e50 0000000000000140 T spurious_entries_start
> ffffffff8ac00f90 000000000000001f T asm_exc_divide_error
> ffffffff8ac00fb0 000000000000001f T asm_exc_overflow
> --
> ffffffff8ac01570 000000000000001f T asm_sysvec_kvm_posted_intr_wakeup_ipi
> ffffffff8ac01590 000000000000001f T asm_sysvec_kvm_posted_intr_nested_ipi
> ffffffff8ac015b0 000000000000001f T asm_sysvec_kvm_asyncpf_interrupt
> ffffffff8ac015d0 T __irqentry_text_end
> ffffffff8ac015d0 T swapgs_restore_regs_and_return_to_usermode
> ffffffff8ac01624 T restore_regs_and_return_to_kernel
> ffffffff8ac01646 T native_irq_return_iret
>
>
> So the __softirqentry_text_start/end range includes only __do_softirq symbol.
>
> And __irqentry_text_start/end includes asm_exc_divide_error,
> asm_exc_overflow, etc.
>
> This looks reasonable.
>
> Now for a random arm64 kernel I see this:
>
> $ nm -nS vmlinux | grep -v "\$x" | grep -C 3 irqentry_text
> ffff800008000008 t $d.1
> ffff800008010008 000000000000000c t __primary_entry_veneer
> ffff800008020000 0000000000000158 t dw_apb_ictl_handle_irq
> ffff800008020000 T __irqentry_text_start
> ffff800008020000 T _stext
> ffff80000802015c 0000000000000d2c T __do_softirq
> ffff80000802015c T __irqentry_text_end
> ffff80000802015c T __softirqentry_text_start
> ffff800008020ebc T __entry_text_start
> ffff800008020ebc T __softirqentry_text_end
> ffff800008021000 0000000000000800 T vectors
> ffff800008021800 000000000000007c t __bad_stack
> ffff80000802187c 0000000000000068 t el1t_64_sync
>
> So the __softirqentry_text_start/end range also includes only
> __do_softirq symbol.
>
> And __irqentry_text_start/end includes only dw_apb_ictl_handle_irq.
>
> I don't know if it's correct for arm64 kernel or not (are there other
> irq entry points?).
>
> If you have other entry points, I think you need to mark them with
> __irq_entry macro, which should place them in the section:
>
> https://elixir.bootlin.com/linux/latest/source/include/linux/interrupt.h#L829
> https://elixir.bootlin.com/linux/latest/A/ident/__irq_entry

Found examples of proper cut points for irq/softirq for arm64 on syzbot:

https://syzkaller.appspot.com/text?tag=CrashReport&x=131be6be880000
Freed by task 2264:
kasan_save_stack+0x2c/0x60 mm/kasan/common.c:45
kasan_set_track+0x2c/0x40 mm/kasan/common.c:52
kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:511
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x124/0x1f0 mm/kasan/common.c:200
__kasan_slab_free+0x18/0x24 mm/kasan/common.c:244
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook+0x9c/0x1bc mm/slub.c:1750
slab_free mm/slub.c:3661 [inline]
__kmem_cache_free+0xa4/0x370 mm/slub.c:3674
kfree+0xdc/0x284 mm/slab_common.c:1007
rcu_free_wq+0x9c/0x10c kernel/workqueue.c:3531
rcu_do_batch kernel/rcu/tree.c:2250 [inline]
rcu_core+0x874/0x1b50 kernel/rcu/tree.c:2510
rcu_core_si+0x10/0x1c kernel/rcu/tree.c:2527
_stext+0x28c/0x107c

https://syzkaller.appspot.com/text?tag=CrashReport&x=1147006cc80000
Freed by task 21:
...
skb_release_all net/core/skbuff.c:916 [inline]
__kfree_skb net/core/skbuff.c:930 [inline]
consume_skb+0xa4/0x17c net/core/skbuff.c:1098
mac80211_hwsim_tx_frame+0x1cc/0x1f8 drivers/net/wireless/mac80211_hwsim.c:2054
mac80211_hwsim_beacon_tx+0x4f0/0x8ec drivers/net/wireless/mac80211_hwsim.c:2116
__iterate_interfaces+0x204/0x460 net/mac80211/util.c:763
ieee80211_iterate_active_interfaces_atomic+0xb4/0x140 net/mac80211/util.c:799
mac80211_hwsim_beacon+0xcc/0x1c8 drivers/net/wireless/mac80211_hwsim.c:2142
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x580/0x10a8 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x158/0x220 kernel/time/hrt

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