On Mon, Feb 28, 2022 at 08:10:18PM +0100, Vlastimil Babka wrote:
> 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?
By the way, I fixed this by allowing stack_depot_init() to be called in
kmem_cache_init() too [1] and Marco suggested that calling
stack_depot_init() depending on slub_debug parameter for simplicity. [2]
I would prefer [2], Would you take a look?
[1] https://lkml.org/lkml/2022/2/27/31
[2] https://lkml.org/lkml/2022/2/28/717
> > 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
> >>
> >>
> >
>
--
Thank you, You are awesome!
Hyeonggon :-)
