Messages in this thread | | | Subject | Re: kmemleak: Early log buffer exceeded | From | Catalin Marinas <> | Date | Thu, 16 Jul 2009 17:53:37 +0100 |
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On Wed, 2009-07-15 at 22:47 +0530, Jaswinder Singh Rajput wrote: > Currently this reporting seems not very impressive and not giving much > useful information : > > kmemleak: Early log buffer exceeded > kmemleak: Kernel memory leak detector disabled > > It should be something like this because it is an error and this will > disable Kernel memory leak detector : > > [ 0.000173] ------------[ cut here ]------------ > [ 0.000186] WARNING: at mm/kmemleak.c:726 log_early+0x39/0xa9() > [ 0.000189] Hardware name: > [ 0.000192] Early log buffer exceeded, please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE > [ 0.000195] Modules linked in: > [ 0.000202] Pid: 0, comm: swapper Not tainted 2.6.31-rc3 #51 > [ 0.000206] Call Trace: > [ 0.000216] [<c102cf74>] warn_slowpath_common+0x60/0x90 > [ 0.000222] [<c102cfd8>] warn_slowpath_fmt+0x24/0x27 > [ 0.000227] [<c109614b>] log_early+0x39/0xa9 > [ 0.000232] [<c109682d>] kmemleak_alloc+0x41/0x4c > [ 0.000241] [<c1093b63>] __kmalloc+0xcb/0x153 > [ 0.000247] [<c1093c04>] alloc_arraycache+0x19/0x50 > [ 0.000253] [<c1093e44>] do_tune_cpucache+0x209/0x35d > [ 0.000259] [<c10940ee>] enable_cpucache+0x58/0x9a > [ 0.000267] [<c14bc6e5>] kmem_cache_init_late+0x21/0xc2 > [ 0.000274] [<c14a8a20>] start_kernel+0x1e5/0x2ba > [ 0.000280] [<c14a8340>] i386_start_kernel+0x6a/0x6f > [ 0.000380] ---[ end trace 4eaa2a86a8e2da22 ]--- > [ 0.000384] kmemleak: Kernel memory leak detector disabled
I'm OK with mentioning DEBUG_KMEMLEAK_EARLY_LOG_SIZE but the stack trace is not relevant here, it can happen in any place which allocates some memory.
> Currently default value of DEBUG_KMEMLEAK_EARLY_LOG_SIZE is 400 which > can be easily exceed-able if debugging is on.
That's why I made it configurable. We can indeed set it to a higher value but that's after 2.6.31. I have a patch in to mark this buffer as __initdata so that it is freed.
> These issues can be fixed like this : > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 12327b2..2eaf8bc 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -362,14 +362,15 @@ config DEBUG_KMEMLEAK > config DEBUG_KMEMLEAK_EARLY_LOG_SIZE > int "Maximum kmemleak early log entries" > depends on DEBUG_KMEMLEAK > - range 200 2000 > - default 400 > + range 256 2048 > + default 512
The power of 2 boundaries is not relevant as this represents the number of elements in an array rather than a size in bytes.
> help > Kmemleak must track all the memory allocations to avoid > reporting false positives. Since memory may be allocated or > freed before kmemleak is initialised, an early log buffer is > - used to store these actions. If kmemleak reports "early log > - buffer exceeded", please increase this value. > + used to store these actions. You need to increase this value, > + if kmemleak reports "Early log buffer exceeded, please increase > + DEBUG_KMEMLEAK_EARLY_LOG_SIZE". > > config DEBUG_KMEMLEAK_TEST > tristate "Simple test for the kernel memory leak detector" > diff --git a/mm/kmemleak.c b/mm/kmemleak.c > index 5aabd41..084e927 100644 > --- a/mm/kmemleak.c > +++ b/mm/kmemleak.c > @@ -722,7 +722,8 @@ static void log_early(int op_type, const void *ptr, size_t size, > struct early_log *log; > > if (crt_early_log >= ARRAY_SIZE(early_log)) { > - pr_warning("Early log buffer exceeded\n"); > + WARN_ONCE(1, KERN_ERR "Early log buffer exceeded, " > + "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n"); > kmemleak_disable(); > return; > }
As I said above, I wouldn't want a stack trace here. Initially, this code called kmemleak_panic() but changed it since the stack trace isn't relevant.
Thanks.
-- Catalin
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