Re: [PATCH v8 20/26] powerpc: book3s64: convert to pin_user_pages() and put_user_page()

2019-12-10 Thread Andrew Morton 
On Mon, 9 Dec 2019 21:53:00 -0800 John Hubbard  wrote:

> > Correction: this is somehow missing the fixes that resulted from Jan Kara's 
> > review (he
> > noted that we can't take a page lock in this context). I must have picked 
> > up the
> > wrong version of it, when I rebased for -rc1.
> > 
> 
> Andrew, given that the series is now in -mm, what's the preferred way for me 
> to fix this?
> Send a v9 version of the whole series? Or something else?

I think a full resend is warranted at this time - it's only been in
there a day and there seem to be quite a number of changes to be made.

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Re: [PATCH v8 20/26] powerpc: book3s64: convert to pin_user_pages() and put_user_page()

2019-12-09 Thread John Hubbard 

On 12/9/19 3:46 PM, John Hubbard wrote:

On 12/9/19 2:53 PM, John Hubbard wrote:
...

@@ -212,10 +211,9 @@ static void mm_iommu_unpin(struct 
mm_iommu_table_group_mem_t *mem)
if (!page)
continue;
  
-		if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)

-   SetPageDirty(page);
+   put_user_pages_dirty_lock(, 1,
+   mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY);
  
-		put_page(page);



Correction: this is somehow missing the fixes that resulted from Jan Kara's 
review (he
noted that we can't take a page lock in this context). I must have picked up the
wrong version of it, when I rebased for -rc1.



Andrew, given that the series is now in -mm, what's the preferred way for me to 
fix this?
Send a v9 version of the whole series? Or something else?

I'm still learning the ropes...

thanks,
--
John Hubbard
NVIDIA


Will fix in the next version (including the commit description). Here's what the
corrected hunk will look like:

@@ -215,7 +214,8 @@ static void mm_iommu_unpin(struct 
mm_iommu_table_group_mem_t *mem)
 if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
 SetPageDirty(page);
  
-   put_page(page);

+   put_user_page(page);
+
 mem->hpas[i] = 0;
 }
  }


thanks,


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Re: [PATCH v8 20/26] powerpc: book3s64: convert to pin_user_pages() and put_user_page()

2019-12-09 Thread John Hubbard 
On 12/9/19 2:53 PM, John Hubbard wrote:
...
> @@ -212,10 +211,9 @@ static void mm_iommu_unpin(struct 
> mm_iommu_table_group_mem_t *mem)
>   if (!page)
>   continue;
>  
> - if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
> - SetPageDirty(page);
> + put_user_pages_dirty_lock(, 1,
> + mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY);
>  
> - put_page(page);


Correction: this is somehow missing the fixes that resulted from Jan Kara's 
review (he
noted that we can't take a page lock in this context). I must have picked up 
the 
wrong version of it, when I rebased for -rc1.

Will fix in the next version (including the commit description). Here's what the
corrected hunk will look like:

@@ -215,7 +214,8 @@ static void mm_iommu_unpin(struct 
mm_iommu_table_group_mem_t *mem)
if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
SetPageDirty(page);
 
-   put_page(page);
+   put_user_page(page);
+
mem->hpas[i] = 0;
}
 }


thanks,
-- 
John Hubbard
NVIDIA
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[PATCH v8 20/26] powerpc: book3s64: convert to pin_user_pages() and put_user_page()

2019-12-09 Thread John Hubbard 
1. Convert from get_user_pages() to pin_user_pages().

2. As required by pin_user_pages(), release these pages via
put_user_page(). In this case, do so via put_user_pages_dirty_lock().

That has the side effect of calling set_page_dirty_lock(), instead
of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.gb...@lst.de

Cc: Jan Kara 
Signed-off-by: John Hubbard 
---
 arch/powerpc/mm/book3s64/iommu_api.c | 12 +---
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/iommu_api.c 
b/arch/powerpc/mm/book3s64/iommu_api.c
index 56cc84520577..fc1670a6fc3c 100644
--- a/arch/powerpc/mm/book3s64/iommu_api.c
+++ b/arch/powerpc/mm/book3s64/iommu_api.c
@@ -103,7 +103,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, 
unsigned long ua,
for (entry = 0; entry < entries; entry += chunk) {
unsigned long n = min(entries - entry, chunk);
 
-   ret = get_user_pages(ua + (entry << PAGE_SHIFT), n,
+   ret = pin_user_pages(ua + (entry << PAGE_SHIFT), n,
FOLL_WRITE | FOLL_LONGTERM,
mem->hpages + entry, NULL);
if (ret == n) {
@@ -167,9 +167,8 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, 
unsigned long ua,
return 0;
 
 free_exit:
-   /* free the reference taken */
-   for (i = 0; i < pinned; i++)
-   put_page(mem->hpages[i]);
+   /* free the references taken */
+   put_user_pages(mem->hpages, pinned);
 
vfree(mem->hpas);
kfree(mem);
@@ -212,10 +211,9 @@ static void mm_iommu_unpin(struct 
mm_iommu_table_group_mem_t *mem)
if (!page)
continue;
 
-   if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
-   SetPageDirty(page);
+   put_user_pages_dirty_lock(, 1,
+   mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY);
 
-   put_page(page);
mem->hpas[i] = 0;
}
 }
-- 
2.24.0

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