site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:from:to:cc:references:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:in-reply-to:thread-index:x-mimeole; bh=IEbueiy/9ImYtAUsRxoWESotyDW25axcwNFbaCe/2cM=; b=MJG1ONd7kLAmBIyLhdFJ379FfU13dTR2Q5RBnHM3oOAqHBtGHSRreZZN0fNl79/oHarO8AM18of844Dqe1R9jhcseyIdVlTeuMbQ0mbzJnCKdCKRhp51BKS2Xx+KSHRwigcIfI4LUjEem96Xl7AxGPPYQaOoOpAacrM0lvW6jOU= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:references:subject:date:message-id:mime-version:content-type:content-transfer-encoding:x-mailer:in-reply-to:thread-index:x-mimeole; b=VSMX92rKfK9In5EHvBDzu8/mlqiYTqcD1wxu3ndQH8w+X7DSN+r10e+PW5Ld1Q+OiqpSEqZl1CIUcOkGnKHgvz2xE5CplU95brq9LYxz2Bv7/JsOZPcRvKQ6wC5ep4+wkc+x5ZbPWYrn+5+xpgrOwKvMQQ9RAxU8Pb7km00U+0U= Thread-index: AchGHDamPyVeCb/GRXOxXrxSMAfcOAOAsMbg Hi Brian, Could you please explain what are the consequences of calling OSMalloc with some spin lock held. I'm using lck_spin_lock() to lock a global variable before OSMalloc and release it once the item allocated has been added to a queue. Besides returned NULL value, is there any other difference between OSMalloc() and OSMalloc_noblock()? In case OSMalloc_noblock() returns NULL can I try allocation immediately? ________________________________ Thanks - vishal shetye -----Original Message----- From: Brian Bergstrand [mailto:brian@classicalguitar.net] Sent: Monday, December 24, 2007 4:31 PM To: Vishal Shetye Cc: darwin-kernel@lists.apple.com Subject: Re: Panic in OSMalloc?? You should not call OSMalloc while holding any lock. If you must do this, then use OSMalloc_noblock() instead - but be prepared to deal with NULL if the request can't be filled. On Dec 24, 2007, at 8:40 AM, Vishal Shetye wrote:

Hi,

I've written a kext that listens on fileop scope. I'm using OSMalloc and OSFree for memory allocation/freeing. I'm getting "thread_invoke: preemption_level 1" panic. Following is the backtrace of panic. OSMalloc() is the last function my kext calls. An area that I suspect is, I'm using same "OSMalloc Tag" in different parts of my module which might call OSMalloc simultaneously. Do I have to malloc with some locking under such scenarios or is it handled by OSMalloc() as I can see calls to mutex_lock() and subsequently to lck_mtx_lock_wait().

What might be the case wherein OSMalloc(), trying to wait will result in such a panic???

Backtrace

#0 Debugger (message=0x3bc46c "panic") at /SourceCache/xnu/ xnu-792.9.72/osfmk/i386/AT386/model_dep.c:706 #1 0x00128b5e in panic (str=0x3bcd50 "thread_invoke: preemption_level %d\n") at /SourceCache/xnu/xnu-792.9.72/osfmk/kern/ debug.c:202 #2 0x001350ce in thread_invoke (old_thread=0x29c7c78, new_thread=0x1b70000, reason=0) at /SourceCache/xnu/xnu-792.9.72/ osfmk/kern/sched_prim.c:1287 #3 0x0013572c in thread_block_reason (continuation=0, parameter=0x0, reason=0) at /SourceCache/xnu/xnu-792.9.72/osfmk/kern/ sched_prim.c:1692 #4 0x001357bd in thread_block (continuation=0) at /SourceCache/xnu/ xnu-792.9.72/osfmk/kern/sched_prim.c:1714 #5 0x0012f297 in lck_mtx_lock_wait (lck=0x13adcb8, holder=0x29cae58) at /SourceCache/xnu/xnu-792.9.72/osfmk/kern/ locks.c:569 #6 0x00194e4e in mutex_lock () #7 0x00141242 in zalloc_canblock (zone=0x13adcb0, canblock=1) at / SourceCache/xnu/xnu-792.9.72/osfmk/kern/zalloc.c:638 #8 0x0012d780 in kalloc_canblock (size=12, canblock=1) at / SourceCache/xnu/xnu-792.9.72/osfmk/kern/kalloc.c:256 #9 0x0012df5f in OSMalloc (size=12, tag=0x2af7600) at /SourceCache/ xnu/xnu-792.9.72/osfmk/kern/kalloc.c:263 #10 0x1f5796fb in ?? () #11 0x1f576c60 in ?? () #12 0x1f573319 in ?? () #13 0x0031810a in kauth_authorize_action (scope=0x1c1ca04, credential=0x26a7204, action=2, arg0=41112608, arg1=4746816, arg2=2, arg3=0) at /SourceCache/xnu/xnu-792.9.72/bsd/kern/ kern_authorization.c:405 #14 0x0031827e in kauth_authorize_fileop (credential=0x26a7204, action=2, arg0=41112608, arg1=4746816) at /SourceCache/xnu/ xnu-792.9.72/bsd/kern/kern_authorization.c:550 #15 0x0032710e in close_internal (p=0x2273000, fd=5, fp=0x1d8e5e0, flags=3) at /SourceCache/xnu/xnu-792.9.72/bsd/kern/kern_descrip.c:1043 #16 0x003272ae in close (p=0x2273000, uap=0x25bef0c, retval=0x25bef50) at /SourceCache/xnu/xnu-792.9.72/bsd/kern/ kern_descrip.c:985 #17 0x0036de6c in unix_syscall (regs=0x29c7ef0) at /SourceCache/xnu/ xnu-792.9.72/bsd/dev/i386/systemcalls.c:201 #18 0x00197ff3 in lo_unix_scall () Cannot access memory at address 0xbffffa98 Cannot access memory at address 0xbffffa9c

Brian Bergstrand <http://www.bergstrand.org/brian/> PGP Key ID: 0xB6C7B6A2 _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com