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    SubjectRe: kmemleak false positive?
    On Thu, Jun 25, 2009 at 10:25:17AM +0100, Catalin Marinas wrote:

    > > kmemleak: backtrace:
    > > kmemleak: [<c04fd8b3>] kmemleak_alloc+0x193/0x2b8
    > > kmemleak: [<c04f5e73>] kmem_cache_alloc+0x11e/0x174
    > > kmemleak: [<c0aae5a7>] debug_objects_mem_init+0x63/0x1d9
    > > kmemleak: [<c0a86a62>] start_kernel+0x2da/0x38d
    > > kmemleak: [<c0a86090>] i386_start_kernel+0x7f/0x98
    > > kmemleak: [<ffffffff>] 0xffffffff
    >
    > It could be a false positive. Do you get some "kmemleak: referenced"
    > messages as well at a later time? In this case, it is just transient
    > "leak", caused maybe by pointers stored on the stack or registers.

    Yes, some time later.

    > Is the obj_pool in lib/debugobjects.c supposed to be empty at the end of
    > the test and all objects freed? The obj_pool is a list and the first
    > elements in this list are from obj_static_pool, which is __initdata.
    > Objects added to the list may be referred by chaining with the
    > obj_static_pool objects but kmemleak doesn't scan __initdata as this is
    > usually freed before kmemleak does its first scan. So, if it is just a
    > transient "leak", kmemleak should later report "kmemleak: referenced" if
    > a kmem_cache_free() is called on any of the reported objects.

    Hmm, it's pretty noisy, and everything it's found so far looks to be
    a false positive.

    > You can mount debugfs on /sys/kerne/debug and read the kmemleak file in
    > there (it triggers a new scan as well).

    Currently prints the acpi traces I already posted.

    > You can also echo stack=on to
    > the above kmemleak file to enable kernel stack scanning.
    >
    > Could you send me your config options for DEBUG_OBJECTS_* and slab
    > allocator so I can try to reproduce this?

    CONFIG_DEBUG_OBJECTS=y
    # CONFIG_DEBUG_OBJECTS_SELFTEST is not set
    CONFIG_DEBUG_OBJECTS_FREE=y
    CONFIG_DEBUG_OBJECTS_TIMERS=y
    CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT=1

    Dave



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