On 2/26/22 08:19, Hyeonggon Yoo wrote:
> On Fri, Feb 25, 2022 at 07:03:13PM +0100, Vlastimil Babka wrote:
>> Hi,
>>
>> this series combines and revives patches from Oliver's last year
>> bachelor thesis (where I was the advisor) that make SLUB's debugfs
>> files alloc_traces and free_traces more useful.
>> The resubmission was blocked on stackdepot changes that are now merged,
>> as explained in patch 2.
>>
>
> Hello. I just started review/testing this series.
>
> it crashed on my system (arm64)
Hmm, interesting. On x86_64 this works for me and stackdepot is allocated
from memblock. arm64 must have memblock freeing happen earlier or something.
(CCing memblock experts)
> I ran with boot parameter slub_debug=U, and without KASAN.
> So CONFIG_STACKDEPOT_ALWAYS_INIT=n.
>
> void * __init memblock_alloc_try_nid(
> phys_addr_t size, phys_addr_t align,
> phys_addr_t min_addr, phys_addr_t max_addr,
> int nid)
> {
> void *ptr;
>
> memblock_dbg("%s: %llu bytes align=0x%llx nid=%d from=%pa max_addr=%pa %pS\n",
> __func__, (u64)size, (u64)align, nid, &min_addr,
> &max_addr, (void *)_RET_IP_);
> ptr = memblock_alloc_internal(size, align,
> min_addr, max_addr, nid, false);
> if (ptr)
> memset(ptr, 0, size); <--- Crash Here
>
> return ptr;
> }
>
> It crashed during create_boot_cache() -> stack_depot_init() ->
> memblock_alloc().
>
> I think That's because, in kmem_cache_init(), both slab and memblock is not
> available. (AFAIU memblock is not available after mem_init() because of
> memblock_free_all(), right?)
Hm yes I see, even in x86_64 version mem_init() calls memblock_free_all().
But then, I would expect stack_depot_init() to detect that memblock_alloc()
returns NULL, we print ""Stack Depot hash table allocation failed,
disabling" and disable it. Instead it seems memblock_alloc() returns
something that's already potentially used by somebody else? Sounds like a bug?
> Thanks!
>
> /*
> * Set up kernel memory allocators
> */
> static void __init mm_init(void)
> {
> /*
> * page_ext requires contiguous pages,
> * bigger than MAX_ORDER unless SPARSEMEM.
> */
> page_ext_init_flatmem();
> init_mem_debugging_and_hardening();
> kfence_alloc_pool();
> report_meminit();
> stack_depot_early_init();
> mem_init();
> mem_init_print_info();
> kmem_cache_init();
> /*
> * page_owner must be initialized after buddy is ready, and also after
> * slab is ready so that stack_depot_init() works properly
> */)
>
>> Patch 1 is a new preparatory cleanup.
>>
>> Patch 2 originally submitted here [1], was merged to mainline but
>> reverted for stackdepot related issues as explained in the patch.
>>
>> Patches 3-5 originally submitted as RFC here [2]. In this submission I
>> have omitted the new file 'all_objects' (patch 3/3 in [2]) as it might
>> be considered too intrusive so I will postpone it for later. The docs
>> patch is adjusted accordingly.
>>
>> Also available in git, based on v5.17-rc1:
>> https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git/log/?h=slub-stackdepot-v1
>>
>> I'd like to ask for some review before I add this to the slab tree.
>>
>> [1] https://lore.kernel.org/all/20210414163434.4376-1-glittao@xxxxxxxxx/
>> [2] https://lore.kernel.org/all/20210521121127.24653-1-glittao@xxxxxxxxx/
>>
>> Oliver Glitta (4):
>> mm/slub: use stackdepot to save stack trace in objects
>> mm/slub: aggregate and print stack traces in debugfs files
>> mm/slub: sort debugfs output by frequency of stack traces
>> slab, documentation: add description of debugfs files for SLUB caches
>>
>> Vlastimil Babka (1):
>> mm/slub: move struct track init out of set_track()
>>
>> Documentation/vm/slub.rst | 61 +++++++++++++++
>> init/Kconfig | 1 +
>> mm/slub.c | 152 +++++++++++++++++++++++++-------------
>> 3 files changed, 162 insertions(+), 52 deletions(-)
>>
>> --
>> 2.35.1
>>
>>
>
