On Mon, Apr 11, 2016 at 04:51:47PM +0200, Alexander Potapenko wrote: > On Mon, Apr 11, 2016 at 4:39 PM, Alexander Potapenko <[email protected]> > wrote: > > On Mon, Apr 11, 2016 at 9:44 AM, Joonsoo Kim <[email protected]> wrote: > >> On Mon, Mar 14, 2016 at 11:43:43AM +0100, Alexander Potapenko wrote: > >>> +depot_stack_handle_t depot_save_stack(struct stack_trace *trace, > >>> + gfp_t alloc_flags) > >>> +{ > >>> + u32 hash; > >>> + depot_stack_handle_t retval = 0; > >>> + struct stack_record *found = NULL, **bucket; > >>> + unsigned long flags; > >>> + struct page *page = NULL; > >>> + void *prealloc = NULL; > >>> + bool *rec; > >>> + > >>> + if (unlikely(trace->nr_entries == 0)) > >>> + goto fast_exit; > >>> + > >>> + rec = this_cpu_ptr(&depot_recursion); > >>> + /* Don't store the stack if we've been called recursively. */ > >>> + if (unlikely(*rec)) > >>> + goto fast_exit; > >>> + *rec = true; > >>> + > >>> + hash = hash_stack(trace->entries, trace->nr_entries); > >>> + /* Bad luck, we won't store this stack. */ > >>> + if (hash == 0) > >>> + goto exit; > >> > >> Hello, > >> > >> why is hash == 0 skipped? > >> > >> Thanks. > > We have to keep a special value to distinguish allocations for which > > we don't have the stack trace for some reason. > > Making 0 such a value seems natural. > Well, the above statement is false. > Because we only compare the hash to the records that are already in > the depot, there's no point in reserving this value.
So, could you make a patch for it? Thanks.
