Re: [PATCH -rt] free_pgtables deadlock

[Ingo Molnar]

* Daniel Walker <dwalker@xxxxxxxxxx> wrote:

> Following is a fix for this deadlock .
> 
> What's happening is task 2 holds the i_mmap_lock from unmap_region(), 
> then it enters zap_page_range() where it tried to acquire the locked 
> mmu_gathers percpu .
> 
> While task 1) holds the mmu_gathers percpu lock from unmap_region() 
> and then tried to aquire i_mmap_lock inside unlink_file_vma() .
> 
> It looks like it's possible to drop the mmu_gathers prior to calling 
> unlink_file_vma() , but it's only done if there's more than one vma .
> 
> This deadlock was seen by Deepak Saxena on an ARM Versatile board.

thanks, applied.

	Ingo
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