LinuxLists.cc - [PATCH v2] mm/slub: initialize stack depot in boot process

2022-03-01 04:00:42

Subject: [PATCH v2] mm/slub: initialize stack depot in boot process

commit ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in
objects") initializes stack depot in cache creation if SLAB_STORE_USER
flag is set.

This can make kernel crash because a cache can be crashed in various
contexts. For example if user sets slub_debug=U, kernel crashes
because create_boot_cache() calls stack_depot_init(), which tries to
allocate hash table using memblock_alloc() if slab is not available.
But memblock is also not available at that time.

This patch solves the problem by initializing stack depot early
in boot process if SLAB_STORE_USER debug flag is set globally
or the flag is set for at least one cache.

[ [email protected]: initialize stack depot depending on slub_debug
parameter instead of allowing stack_depot_init() to be called
during kmem_cache_init() for simplicity. ]

[ [email protected]: parse slub_debug parameter in setup_slub_debug()
and initialize stack depot in stack_depot_early_init(). ]

Link: https://lore.kernel.org/all/YhyeaP8lrzKgKm5A@ip-172-31-19-208.ap-northeast-1.compute.internal/
Fixes: ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in objects")
Signed-off-by: Hyeonggon Yoo <[email protected]>
---
include/linux/slab.h | 6 ++++++
include/linux/stackdepot.h | 3 ++-
mm/slub.c | 18 +++++++++++++++---
3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 37bde99b74af..062128e0db10 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -763,6 +763,12 @@ extern void kvfree_sensitive(const void *addr, size_t len);
unsigned int kmem_cache_size(struct kmem_cache *s);
void __init kmem_cache_init_late(void);

+#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_STACKDEPOT)
+int slab_stack_depot_init(void);
+#else
+int slab_stack_depot_init(void) { return 0; }
+#endif
+
#if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
int slab_prepare_cpu(unsigned int cpu);
int slab_dead_cpu(unsigned int cpu);
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 17f992fe6355..a813a2673c48 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -12,6 +12,7 @@
#define _LINUX_STACKDEPOT_H

#include <linux/gfp.h>
+#include <linux/slab.h>

typedef u32 depot_stack_handle_t;

@@ -32,7 +33,7 @@ int stack_depot_init(void);
#ifdef CONFIG_STACKDEPOT_ALWAYS_INIT
static inline int stack_depot_early_init(void) { return stack_depot_init(); }
#else
-static inline int stack_depot_early_init(void) { return 0; }
+static inline int stack_depot_early_init(void) { return slab_stack_depot_init(); }
#endif

depot_stack_handle_t stack_depot_save(unsigned long *entries,
diff --git a/mm/slub.c b/mm/slub.c
index a74afe59a403..2419fc3cc9f3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -646,6 +646,14 @@ static slab_flags_t slub_debug;

static char *slub_debug_string;
static int disable_higher_order_debug;
+static bool init_stack_depot;
+
+int slab_stack_depot_init(void)
+{
+ if (init_stack_depot)
+ stack_depot_init();
+ return 0;
+}

/*
* slub is about to manipulate internal object metadata. This memory lies
@@ -1531,6 +1539,8 @@ static int __init setup_slub_debug(char *str)
global_slub_debug_changed = true;
} else {
slab_list_specified = true;
+ if (flags & SLAB_STORE_USER)
+ init_stack_depot = true;
}
}

@@ -1546,6 +1556,10 @@ static int __init setup_slub_debug(char *str)
global_flags = slub_debug;
slub_debug_string = saved_str;
}
+
+ if (global_flags & SLAB_STORE_USER)
+ init_stack_depot = true;
+
out:
slub_debug = global_flags;
if (slub_debug != 0 || slub_debug_string)
@@ -1556,6 +1570,7 @@ static int __init setup_slub_debug(char *str)
static_branch_unlikely(&init_on_free)) &&
(slub_debug & SLAB_POISON))
pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n");
+
return 1;
}

@@ -4221,9 +4236,6 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
s->remote_node_defrag_ratio = 1000;
#endif

- if (s->flags & SLAB_STORE_USER && IS_ENABLED(CONFIG_STACKDEPOT))
- stack_depot_init();
-
/* Initialize the pre-computed randomized freelist if slab is up */
if (slab_state >= UP) {
if (init_cache_random_seq(s))
--
2.33.1

2022-03-01 05:37:14

by Hyeonggon Yoo

[permalink] [raw]

Subject: Re: [PATCH v2] mm/slub: initialize stack depot in boot process

On Tue, Mar 01, 2022 at 03:36:38AM +0000, Hyeonggon Yoo wrote:
> commit ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in
> objects") initializes stack depot in cache creation if SLAB_STORE_USER
> flag is set.
>
> This can make kernel crash because a cache can be crashed in various
> contexts. For example if user sets slub_debug=U, kernel crashes
> because create_boot_cache() calls stack_depot_init(), which tries to
> allocate hash table using memblock_alloc() if slab is not available.
> But memblock is also not available at that time.
>
> This patch solves the problem by initializing stack depot early
> in boot process if SLAB_STORE_USER debug flag is set globally
> or the flag is set for at least one cache.
>

Hello Vlastimil, would you pick this up into slub-stackdepot-v1,
or fold it into original patch (2/5)?

Thanks!

--
Thank you, You are awesome!
Hyeonggon :-)

> [ [email protected]: initialize stack depot depending on slub_debug
> parameter instead of allowing stack_depot_init() to be called
> during kmem_cache_init() for simplicity. ]
>
> [ [email protected]: parse slub_debug parameter in setup_slub_debug()
> and initialize stack depot in stack_depot_early_init(). ]
>
> Link: https://lore.kernel.org/all/YhyeaP8lrzKgKm5A@ip-172-31-19-208.ap-northeast-1.compute.internal/
> Fixes: ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in objects")
> Signed-off-by: Hyeonggon Yoo <[email protected]>
> ---
> include/linux/slab.h | 6 ++++++
> include/linux/stackdepot.h | 3 ++-
> mm/slub.c | 18 +++++++++++++++---
> 3 files changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 37bde99b74af..062128e0db10 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -763,6 +763,12 @@ extern void kvfree_sensitive(const void *addr, size_t len);
> unsigned int kmem_cache_size(struct kmem_cache *s);
> void __init kmem_cache_init_late(void);
>
> +#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_STACKDEPOT)
> +int slab_stack_depot_init(void);
> +#else
> +int slab_stack_depot_init(void) { return 0; }
> +#endif
> +
> #if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
> int slab_prepare_cpu(unsigned int cpu);
> int slab_dead_cpu(unsigned int cpu);
> diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
> index 17f992fe6355..a813a2673c48 100644
> --- a/include/linux/stackdepot.h
> +++ b/include/linux/stackdepot.h
> @@ -12,6 +12,7 @@
> #define _LINUX_STACKDEPOT_H
>
> #include <linux/gfp.h>
> +#include <linux/slab.h>
>
> typedef u32 depot_stack_handle_t;
>
> @@ -32,7 +33,7 @@ int stack_depot_init(void);
> #ifdef CONFIG_STACKDEPOT_ALWAYS_INIT
> static inline int stack_depot_early_init(void) { return stack_depot_init(); }
> #else
> -static inline int stack_depot_early_init(void) { return 0; }
> +static inline int stack_depot_early_init(void) { return slab_stack_depot_init(); }
> #endif
>
> depot_stack_handle_t stack_depot_save(unsigned long *entries,
> diff --git a/mm/slub.c b/mm/slub.c
> index a74afe59a403..2419fc3cc9f3 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -646,6 +646,14 @@ static slab_flags_t slub_debug;
>
> static char *slub_debug_string;
> static int disable_higher_order_debug;
> +static bool init_stack_depot;
> +
> +int slab_stack_depot_init(void)
> +{
> + if (init_stack_depot)
> + stack_depot_init();
> + return 0;
> +}
>
> /*
> * slub is about to manipulate internal object metadata. This memory lies
> @@ -1531,6 +1539,8 @@ static int __init setup_slub_debug(char *str)
> global_slub_debug_changed = true;
> } else {
> slab_list_specified = true;
> + if (flags & SLAB_STORE_USER)
> + init_stack_depot = true;
> }
> }
>
> @@ -1546,6 +1556,10 @@ static int __init setup_slub_debug(char *str)
> global_flags = slub_debug;
> slub_debug_string = saved_str;
> }
> +
> + if (global_flags & SLAB_STORE_USER)
> + init_stack_depot = true;
> +
> out:
> slub_debug = global_flags;
> if (slub_debug != 0 || slub_debug_string)
> @@ -1556,6 +1570,7 @@ static int __init setup_slub_debug(char *str)
> static_branch_unlikely(&init_on_free)) &&
> (slub_debug & SLAB_POISON))
> pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n");
> +
> return 1;
> }
>
> @@ -4221,9 +4236,6 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
> s->remote_node_defrag_ratio = 1000;
> #endif
>
> - if (s->flags & SLAB_STORE_USER && IS_ENABLED(CONFIG_STACKDEPOT))
> - stack_depot_init();
> -
> /* Initialize the pre-computed randomized freelist if slab is up */
> if (slab_state >= UP) {
> if (init_cache_random_seq(s))
> --
> 2.33.1

2022-03-01 07:25:55

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v2] mm/slub: initialize stack depot in boot process

Hi Hyeonggon,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on vbabka/slub-stackdepot-v1]
[also build test ERROR on linus/master v5.17-rc6 next-20220228]
[cannot apply to hnaz-mm/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Hyeonggon-Yoo/mm-slub-initialize-stack-depot-in-boot-process/20220301-113825
base: https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git slub-stackdepot-v1
config: i386-tinyconfig (https://download.01.org/0day-ci/archive/20220301/[email protected]/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/0day-ci/linux/commit/dd9dbeec7444b13b510dc4a863e9593d1799f965
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Hyeonggon-Yoo/mm-slub-initialize-stack-depot-in-boot-process/20220301-113825
git checkout dd9dbeec7444b13b510dc4a863e9593d1799f965
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

ld: arch/x86/kernel/ebda.o: in function `slab_stack_depot_init':
>> ebda.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: init/main.o: in function `slab_stack_depot_init':
main.c:(.text+0x32): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: init/do_mounts.o: in function `slab_stack_depot_init':
do_mounts.c:(.text+0x5): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: init/noinitramfs.o: in function `slab_stack_depot_init':
noinitramfs.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: init/init_task.o: in function `slab_stack_depot_init':
init_task.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/entry/syscall_32.o: in function `slab_stack_depot_init':
syscall_32.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/entry/common.o: in function `slab_stack_depot_init':
common.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/entry/vdso/vma.o: in function `slab_stack_depot_init':
vma.c:(.text+0x1d0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/entry/vdso/extable.o: in function `slab_stack_depot_init':
extable.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/core.o: in function `slab_stack_depot_init':
core.c:(.text+0x903): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/amd/core.o: in function `slab_stack_depot_init':
core.c:(.text+0x70b): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/core.o: in function `slab_stack_depot_init':
core.c:(.text+0x1cbc): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/bts.o: in function `slab_stack_depot_init':
bts.c:(.text+0x6b2): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/ds.o: in function `slab_stack_depot_init':
ds.c:(.text+0x14ad): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/knc.o: in function `slab_stack_depot_init':
knc.c:(.text+0x2b1): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/lbr.o: in function `slab_stack_depot_init':
lbr.c:(.text+0x6c8): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/p4.o: in function `slab_stack_depot_init':
p4.c:(.text+0x5f8): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/p6.o: in function `slab_stack_depot_init':
p6.c:(.text+0xc4): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/intel/pt.o: in function `slab_stack_depot_init':
pt.c:(.text+0x641): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/events/zhaoxin/core.o: in function `slab_stack_depot_init':
core.c:(.text+0x460): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/realmode/init.o: in function `slab_stack_depot_init':
init.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/process_32.o: in function `slab_stack_depot_init':
process_32.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/signal.o: in function `slab_stack_depot_init':
signal.c:(.text+0x5b4): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/traps.o: in function `slab_stack_depot_init':
traps.c:(.text+0x288): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/idt.o: in function `slab_stack_depot_init':
idt.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/irq.o: in function `slab_stack_depot_init':
irq.c:(.text+0x4f): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/irq_32.o: in function `slab_stack_depot_init':
irq_32.c:(.text+0x1): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/dumpstack_32.o: in function `slab_stack_depot_init':
dumpstack_32.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/time.o: in function `slab_stack_depot_init':
time.c:(.text+0xd): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/ioport.o: in function `slab_stack_depot_init':
ioport.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/dumpstack.o: in function `slab_stack_depot_init':
dumpstack.c:(.text+0x11e): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/nmi.o: in function `slab_stack_depot_init':
nmi.c:(.text+0x74): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/setup.o: in function `slab_stack_depot_init':
setup.c:(.text+0x3): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/x86_init.o: in function `slab_stack_depot_init':
x86_init.c:(.text+0x39): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/i8259.o: in function `slab_stack_depot_init':
i8259.c:(.text+0x2c4): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/irqinit.o: in function `slab_stack_depot_init':
irqinit.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/irq_work.o: in function `slab_stack_depot_init':
irq_work.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/probe_roms.o: in function `slab_stack_depot_init':
probe_roms.c:(.text+0x1a3): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/sys_ia32.o: in function `slab_stack_depot_init':
sys_ia32.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/bootflag.o: in function `slab_stack_depot_init':
bootflag.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/e820.o: in function `slab_stack_depot_init':
e820.c:(.text+0xbf): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/pci-dma.o: in function `slab_stack_depot_init':
pci-dma.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/quirks.o: in function `slab_stack_depot_init':
quirks.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/topology.o: in function `slab_stack_depot_init':
topology.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/kdebugfs.o: in function `slab_stack_depot_init':
kdebugfs.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/alternative.o: in function `slab_stack_depot_init':
alternative.c:(.text+0x320): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/hw_breakpoint.o: in function `slab_stack_depot_init':
hw_breakpoint.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/rtc.o: in function `slab_stack_depot_init':
rtc.c:(.text+0x41): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/pci-iommu_table.o: in function `slab_stack_depot_init':
pci-iommu_table.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/process.o: in function `slab_stack_depot_init':
process.c:(.text+0xcf): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here
ld: arch/x86/kernel/fpu/init.o: in function `slab_stack_depot_init':
init.c:(.text+0x0): multiple definition of `slab_stack_depot_init'; arch/x86/kernel/head32.o:head32.c:(.text+0x0): first defined here

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

2022-03-01 08:42:28

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v2] mm/slub: initialize stack depot in boot process

2022-03-01 10:05:42

by Hyeonggon Yoo

[permalink] [raw]

Subject: [PATCH v3] mm/slub: initialize stack depot in boot process

commit ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in
objects") initializes stack depot in cache creation if SLAB_STORE_USER
flag is set.

This can make kernel crash because a cache can be crashed in various
contexts. For example if user sets slub_debug=U, kernel crashes
because create_boot_cache() calls stack_depot_init(), which tries to
allocate hash table using memblock_alloc() if slab is not available.
But memblock is also not available at that time.

This patch solves the problem by initializing stack depot early
in boot process if SLAB_STORE_USER debug flag is set globally
or the flag is set for at least one cache.

[ [email protected]: initialize stack depot depending on slub_debug
parameter instead of allowing stack_depot_init() to be called
during kmem_cache_init() for simplicity. ]

[ [email protected]: parse slub_debug parameter in setup_slub_debug()
and initialize stack depot in stack_depot_early_init(). ]

[ [email protected]: Fix build error. ]

Link: https://lore.kernel.org/all/YhyeaP8lrzKgKm5A@ip-172-31-19-208.ap-northeast-1.compute.internal/
Fixes: ba10d4b46655 ("mm/slub: use stackdepot to save stack trace in objects")
Signed-off-by: Hyeonggon Yoo <[email protected]>
---
include/linux/slab.h | 1 +
include/linux/stackdepot.h | 3 ++-
mm/slab.c | 5 +++++
mm/slob.c | 5 +++++
mm/slub.c | 19 ++++++++++++++++---
5 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 37bde99b74af..d2b0f8f9e5e6 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -762,6 +762,7 @@ extern void kvfree_sensitive(const void *addr, size_t len);

unsigned int kmem_cache_size(struct kmem_cache *s);
void __init kmem_cache_init_late(void);
+int __init slab_stack_depot_init(void);

#if defined(CONFIG_SMP) && defined(CONFIG_SLAB)
int slab_prepare_cpu(unsigned int cpu);
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 17f992fe6355..a813a2673c48 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -12,6 +12,7 @@
#define _LINUX_STACKDEPOT_H

#include <linux/gfp.h>
+#include <linux/slab.h>

typedef u32 depot_stack_handle_t;

@@ -32,7 +33,7 @@ int stack_depot_init(void);
#ifdef CONFIG_STACKDEPOT_ALWAYS_INIT
static inline int stack_depot_early_init(void) { return stack_depot_init(); }
#else
-static inline int stack_depot_early_init(void) { return 0; }
+static inline int stack_depot_early_init(void) { return slab_stack_depot_init(); }
#endif

depot_stack_handle_t stack_depot_save(unsigned long *entries,
diff --git a/mm/slab.c b/mm/slab.c
index ddf5737c63d9..c7f929665fbe 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1196,6 +1196,11 @@ static void __init set_up_node(struct kmem_cache *cachep, int index)
}
}

+int __init slab_stack_depot_init(void)
+{
+ return 0;
+}
+
/*
* Initialisation. Called after the page allocator have been initialised and
* before smp_init().
diff --git a/mm/slob.c b/mm/slob.c
index 60c5842215f1..7597c219f061 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -725,3 +725,8 @@ void __init kmem_cache_init_late(void)
{
slab_state = FULL;
}
+
+int __init slab_stack_depot_init(void)
+{
+ return 0;
+}
diff --git a/mm/slub.c b/mm/slub.c
index a74afe59a403..8f130f917977 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -646,6 +646,16 @@ static slab_flags_t slub_debug;

static char *slub_debug_string;
static int disable_higher_order_debug;
+static bool __initdata init_stack_depot;
+
+int __init slab_stack_depot_init(void)
+{
+#ifdef CONFIG_STACKDEPOT
+ if (init_stack_depot)
+ stack_depot_init();
+#endif
+ return 0;
+}

/*
* slub is about to manipulate internal object metadata. This memory lies
@@ -1531,6 +1541,8 @@ static int __init setup_slub_debug(char *str)
global_slub_debug_changed = true;
} else {
slab_list_specified = true;
+ if (flags & SLAB_STORE_USER)
+ init_stack_depot = true;
}
}

@@ -1546,6 +1558,10 @@ static int __init setup_slub_debug(char *str)
global_flags = slub_debug;
slub_debug_string = saved_str;
}
+
+ if (global_flags & SLAB_STORE_USER)
+ init_stack_depot = true;
+
out:
slub_debug = global_flags;
if (slub_debug != 0 || slub_debug_string)
@@ -4221,9 +4237,6 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
s->remote_node_defrag_ratio = 1000;
#endif

- if (s->flags & SLAB_STORE_USER && IS_ENABLED(CONFIG_STACKDEPOT))
- stack_depot_init();
-
/* Initialize the pre-computed randomized freelist if slab is up */
if (slab_state >= UP) {
if (init_cache_random_seq(s))
--
2.33.1