On Fri, Jun 18, 2010 at 6:30 PM, Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > On Fri, 2010-06-18 at 09:11 +0100, Sankar P wrote: >> On Thu, Jun 17, 2010 at 11:06 PM, Luis R. Rodriguez >> <lrodriguez@xxxxxxxxxxx> wrote: >> > On Thu, Jun 17, 2010 at 02:21:56AM -0700, Sankar P wrote: >> >> Hi, >> >> >> >> I wanted to detect memory leaks in one of my kernel modules. So I >> >> built Linus' tree with the following config options enabled (on top >> >> of make defconfig) >> >> >> >> CONFIG_DEBUG_KMEMLEAK=y >> >> CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE=400 >> >> CONFIG_DEBUG_KMEMLEAK_TEST=y >> >> >> >> If I boot with this kernel, debugfs is automatically mounted. But I do >> >> not have the file: >> >> >> >> /sys/kernel/debug/kmemleak >> >> >> >> created at all. There are other files like kprobes in the mounted >> >> /sys/kernel/debug directory btw. So I am not able to detect any of the >> >> memory leaks. Is there anything I am doing wrong or missing (or) is >> >> this a bug in kmemleak ? >> >> >> >> Please let me know your suggestions to fix this and get memory leaks >> >> reporting working. Thanks. >> >> >> >> The full .config file is also attached with this mail. Sorry for the >> >> attachment, I did not want to paste 5k lines in the mail. Sorry if it >> >> is wrong. >> > >> > >> > This is odd.. Do you see this message on your kernel ring buffer? >> > >> > Failed to create the debugfs kmemleak file >> > >> >> I dont see such an error in the dmesg output. But I got another >> interesting error: >> >> [ 0.000000] kmemleak: Early log buffer exceeded, please increase >> DEBUG_KMEMLEAK_EARLY_LOG_SIZE >> [ 0.000000] kmemleak: Kernel memory leak detector disabled > > You would need to increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE. The default of > 400 seems ok for me but it may not work with some other kernel > configurations (that's a static array for logging memory allocations > before the kmemleak is fully initialised and can start tracking them). > >> But after that also, I see some other lines like: >> >> [ 0.511641] kmemleak: vmalloc(64) = f7857000 >> [ 0.511645] kmemleak: vmalloc(64) = f785a000 > > This is because you compiler the test module into the kernel > (DEBUG_KMEMLEAK_TEST). It's not kmemleak printing this but it's testing > module (which leaks memory on purpose). > >> The variable DEBUG_KMEMLEAK_EARLY_LOG_SIZE was set to 400 by default. >> I changed it to 4000 and then 40000 (may be should try < 32567 ?) but >> still I get the same error message and the file >> /sys/kernel/debug/kmem* is never created at all. > > This shouldn't usually happen with values greater than 2000. From your > kernel log, the version seems to be 2.6.32. Do you have the same > problems with 2.6.35-rc3? > > Your .config seems to refer to the 2.6.35-rc3 kernel - are you checking > the right image? > Ah sorry. I am testing by ssh into a remote machine. After installing my kernel (after increasing the DEBUG_KMEMLEAK_EARLY_LOG_SIZE), Before rebooting, I forgot to change the default-kernel this time. I will check once again and will let you know. Thank you a lot for the "dmesg" pointer. -- Sankar P http://psankar.blogspot.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href