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    SubjectRe: [PATCH 01/15] kmemleak: Add the base support
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    On Mon, 2008-12-01 at 08:49 +0200, Pekka Enberg wrote:
    > On Mon, Dec 1, 2008 at 7:39 AM, Yasunori Goto <y-goto@jp.fujitsu.com> wrote:
    > >> +/*
    > >> + * Insert a pointer into the pointer hash table.
    > >> + */
    > >> +static inline void create_object(unsigned long ptr, size_t size, int ref_count)
    > >> +{
    > >> + unsigned long flags;
    > >> + struct memleak_object *object;
    > >> + struct prio_tree_node *node;
    > >> + struct stack_trace trace;
    > >> +
    > >> + object = kmem_cache_alloc(object_cache, GFP_ATOMIC);
    > >> + if (!object)
    > >> + panic("kmemleak: cannot allocate a memleak_object structure\n");
    > >
    > > IIRC, GFP_ATOMIC allocation sometimes fails. (ex. when page cache occupies all
    > > area). It seems to be easy to panic. Is it intended?
    >
    > Yup, GFP_ATOMIC can fail as can any memory allocation on out-of-memory
    > conditions unless you specify GFP_NOFAIL which will either succeed or
    > lock up the box. I think you can just WARN_ON() here? However, it's
    > probably safer to pass gfp flags from the callers here; otherwise we
    > end up doing tons of GFP_ATOMIC allocations which is not healthy in
    > general.

    Yes, good idea, GFP_ATOMIC isn't always needed.

    > Also, I see some other BUG_ON() calls in the code which probably
    > should be converted to WARN_ON() as well.

    This was also raised in the past by Ingo and it's on my to-do list to
    fix. Basically, if an allocation for internal kmemleak structures fails,
    kmemleak should print a warning and disable the tracing since further
    leak reports are irrelevant. Once I add the run-time kmemleak
    configuration/disabling, I'll change the BUG_ON and panic calls to
    something less severe.

    --
    Catalin



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