Messages in this thread |  | | Date | Wed, 21 Feb 2007 16:50:23 -0500 (EST) | From | Alan Stern <> | Subject | Re: [linux-usb-devel] 2.6.20 kernel hang with USB drive and vfat doing ftruncate |
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On Wed, 21 Feb 2007, Andrew Morton wrote:
> On Wed, 21 Feb 2007 16:22:17 -0500 (EST) > Alan Stern <stern@rowland.harvard.edu> wrote: > > > On Wed, 21 Feb 2007, Andrew Morton wrote: > > > > > > > It seems like usb-storage and aio are completely off in the weeds. > > > > > Ideas? > > > > > > > > It seems usb-storage should remove some kmalloc and use mempool() for > > > > urb... Is someone working on this? And idea? > > > > > > I think Pete said that we're supposed to be using GFP_NOIO in there. > > > > We _are_ using it. > > How admirably prompt.
Shucks, we've been using it for years...
> > > 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:
Not having experienced the problem, I can't confirm the fix. However...
> + if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) {
Is that really the correct test? I don't know enough about the memory management subsystem to say one way or the other. What's special about having both flags set?
> + /* > + * The caller might hold locks which can prevert IO completion --------------------------------------------------------------^ Typo
Although perhaps "prevert" is an acceptable neologism in this context.
> + * or progress in the filesystem. So we cannot just sit here > + * waiting for IO to complete. > + */
Alan Stern
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