Re: [PATCH 2/2] mm: Document handle_mm_fault()

From: Steven Rostedt
Date: Tue Jun 28 2011 - 13:04:52 EST


On Tue, 2011-06-28 at 12:47 -0400, Steven Rostedt wrote:
> -
> mm/memory.c | 22 ++++++++++++++++++++--
> 1 files changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 5371b5e..3cf30f6 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3378,8 +3378,26 @@ unlock:
> return 0;
> }
>
> -/*
> - * By the time we get here, we already hold the mm semaphore
> +/**
> + * handle_mm_fault - main routine for handling page faults
> + * @mm: the mm_struct of the target address space
> + * @vma: vm_area_struct holding the applicable pages
> + * @address: the address that took the fault
> + * @flags: flags modifying lookup behaviour
> + *
> + * Must have @mm->mmap_sem held.
> + *
> + * Note: if @flags has FAULT_FLAG_ALLOW_RETRY set then the mmap_sem
> + * may be released if it failed to arquire the page_lock. If the

s/arquire/acquire/

Hmm, I thought I fixed that. I better test the first patch again, in
case it has issues in it that I thought I fixed.

-- Steve

> + * mmap_sem is released then it will return VM_FAULT_RETRY set.
> + * This is to keep the time mmap_sem is held when the page_lock
> + * is taken for IO.
> + * Exception: If FAULT_FLAG_RETRY_NOWAIT is set, then it will
> + * not release the mmap_sem, but will still return VM_FAULT_RETRY
> + * if it failed to acquire the page_lock.
> + * This is for helping virtualization. See get_user_page_nowait().
> + *
> + * Returns status flags based on the VM_FAULT_* flags in <linux/mm.h>
> */
> int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
> unsigned long address, unsigned int flags)


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