On 5/25/21 9:38 AM, Faiyaz Mohammed wrote: > alloc_calls and free_calls implementation in sysfs have two issues, > one is PAGE_SIZE limitiation of sysfs and other is it does not adhere > to "one value per file" rule. > > To overcome this issues, move the alloc_calls and free_calls implemeation > to debugfs. > > Rename the alloc_calls/free_calls to alloc_traces/free_traces, > to be inline with what it does. > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> These were IIRC bot reports for some bugs in the previous versions, so keeping the Reported-by: for the whole patch is misleading - these were not reports for the sysfs issues this patch fixes by moving the files to debugfs. > Signed-off-by: Faiyaz Mohammed <faiyazm@xxxxxxxxxxxxxx> > --- > changes in V7: > - Drop the older alloc_calls and free_calls interface. > changes in v6: > - https://lore.kernel.org/linux-mm/1621341949-26762-1-git-send-email-faiyazm@xxxxxxxxxxxxxx/ > > changes in v5: > - https://lore.kernel.org/linux-mm/1620296523-21922-1-git-send-email-faiyazm@xxxxxxxxxxxxxx/ > > changes in v4: > - https://lore.kernel.org/linux-mm/1618583239-18124-1-git-send-email-faiyazm@xxxxxxxxxxxxxx/ > > changes in v3: > - https://lore.kernel.org/linux-mm/1617712064-12264-1-git-send-email-faiyazm@xxxxxxxxxxxxxx/ > > changes in v2: > - https://lore.kernel.org/linux-mm/3ac1d3e6-6207-96ad-16a1-0f5139d8b2b5@xxxxxxxxxxxxxx/ > > changes in v1: > - https://lore.kernel.org/linux-mm/1610443287-23933-1-git-send-email-faiyazm@xxxxxxxxxxxxxx/ > > include/linux/slub_def.h | 8 ++ > mm/slab_common.c | 9 ++ > mm/slub.c | 353 ++++++++++++++++++++++++++++++++++------------- > 3 files changed, 276 insertions(+), 94 deletions(-) I don't see any of the symlinks under /sys/kernel/debug/slab/, so I think the aliases handling code is wrong, and I can see at least two reasons why it could be: > @@ -4525,6 +4535,8 @@ __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, > s->refcount--; > s = NULL; > } > + > + debugfs_slab_alias(s, name); Here you might be calling debugfs_slab_alias() with NULL if the sysfs_slab_alias() above returned true. > } > > return s; ... > +static int __init slab_debugfs_init(void) > +{ > + struct kmem_cache *s; > + > + slab_debugfs_root = debugfs_create_dir("slab", NULL); > + > + slab_state = FULL; > + > + list_for_each_entry(s, &slab_caches, list) > + debugfs_slab_add(s); > + > + while (alias_list) { > + struct saved_alias *al = alias_list; alias_list a single list and both slab_sysfs_init() and slab_debugfs_init() flush it. So only the init call that happens to be called first, does actually find an unflushed list. I think you need to use a separate list for debugfs (simpler) or a shared list with both sysfs and debugfs processing (probably more complicated). And finally a question, perhaps also for Greg. With sysfs, we hand out the lifecycle of struct kmem_cache to sysfs, to ensure we are not reading sysfs files of a cache that has been removed. But with debugfs, what are the guarantees that things won't blow up when a debugfs file is being read while somebody calls kmem_cache_destroy() on the cache? > + > + alias_list = alias_list->next; > + > + debugfs_slab_alias(al->s, al->name); > + > + kfree(al); > + } > + > + return 0; > + > +} > +__initcall(slab_debugfs_init); > +#endif > /* > * The /proc/slabinfo ABI > */ >
