Re: [linux-usb-devel] 2.6.20 kernel hang with USB drive and vfat doing ftruncate

From: Kumar Gala
Date: Thu Feb 22 2007 - 13:21:49 EST

Not that it'll help much: the VM calls throttle_vm_writeout() for GFP_NOIO
and GFP_NOFS allocations, which is a bug. Because if the caller holds
locks which prevent filesystem or IO progress, we deadlock.

I'll fix the VM if someone else fixes USB ;)

What else needs to be fixed?

Would be nice if someone can confirm that this fixes it:

Doesn't seem to help my problem in a quick test, will get more data in the morning.

Well, I didn't realize the patch you sent via mm-commits and the one here are actually different. I noticed that mm-commits one has:

+ if ((gfp_mask & (__GFP_FS|__GFP_IO)) != __GFP_FS|__GFP_IO) {


+ if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) {

The second seems to make more sense. I tested with the first last night which didn't help.

With the proper patch in place things look good. Is this a candidate for 2.6.20-stable?

- k
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