Subject: Re: linux-next: manual merge of the char-misc.current tree with the mm-hotfixes tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 19 Aug 2022 18:40:27 +1000

Hi Greg,

On Fri, 19 Aug 2022 08:36:21 +0200 Greg KH <[email-masked]> wrote:
>
> On Fri, Aug 19, 2022 at 08:28:18AM +1000, Stephen Rothwell wrote:
> > 
> > Today's linux-next merge of the char-misc.current tree got a conflict in:
> > 
> >   drivers/android/binder_alloc.c
> > 
> > between commit:
> > 
> >   b3bb668f3dc6 ("binder_alloc: add missing mmap_lock calls when using the VMA")
> > 
> > from the mm-hotfixes tree and commit:
> > 
> >   d6f35446d076 ("binder_alloc: Add missing mmap_lock calls when using the VMA")
> > 
> > from the char-misc.current tree.
> > 
> > I fixed it up (I used the latter as it was committed later even though
> > the author times were the same) and can carry the fix as necessary. This
> > is now fixed as far as linux-next is concerned, but any non trivial
> > conflicts should be mentioned to your upstream maintainer when your tree
> > is submitted for merging.  You may also want to consider cooperating
> > with the maintainer of the conflicting tree to minimise any particularly
> > complex conflicts.  
> 
> These should be identical, if not, something went wrong :(

Something went wrong :-)

$ git range-diff b3bb668f3dc6^..b3bb668f3dc6 d6f35446d076^..d6f35446d076
1:  b3bb668f3dc6 ! 1:  d6f35446d076 binder_alloc: add missing mmap_lock calls when using the VMA
    @@ Metadata
     Author: Liam Howlett <[email-masked]>
     
      ## Commit message ##
    -    binder_alloc: add missing mmap_lock calls when using the VMA
    +    binder_alloc: Add missing mmap_lock calls when using the VMA
     
    -    Take the mmap_read_lock() when using the VMA in binder_alloc_print_pages()
    -    and when checking for a VMA in binder_alloc_new_buf_locked().
    +    Take the mmap_read_lock() when using the VMA in
    +    binder_alloc_print_pages() and when checking for a VMA in
    +    binder_alloc_new_buf_locked().
     
         It is worth noting binder_alloc_new_buf_locked() drops the VMA read lock
    -    after it verifies a VMA exists, but may be taken again deeper in the call
    -    stack, if necessary.
    +    after it verifies a VMA exists, but may be taken again deeper in the
    +    call stack, if necessary.
     
    -    Link: https://lkml.kernel.org/r/[email-masked]
    -    Fixes: a43cfc87caaf ("android: binder: stop saving a pointer to the VMA")
    -    Signed-off-by: Liam R. Howlett <[email-masked]>
    +    Fixes: a43cfc87caaf (android: binder: stop saving a pointer to the VMA)
    +    Cc: stable <[email-masked]>
         Reported-by: Ondrej Mosnacek <[email-masked]>
    -    Reported-by: <[email-masked]>
    -    Acked-by: Carlos Llamas <[email-masked]>
    +    Reported-by: [email-masked]
         Tested-by: Ondrej Mosnacek <[email-masked]>
    -    Cc: Minchan Kim <[email-masked]>
    -    Cc: Christian Brauner (Microsoft) <[email-masked]>
    -    Cc: Greg Kroah-Hartman <[email-masked]>
    -    Cc: Hridya Valsaraju <[email-masked]>
    -    Cc: Joel Fernandes <[email-masked]>
    -    Cc: Martijn Coenen <[email-masked]>
    -    Cc: Suren Baghdasaryan <[email-masked]>
    -    Cc: Todd Kjos <[email-masked]>
    -    Cc: Matthew Wilcox (Oracle) <[email-masked]>
    -    Cc: "Arve Hjønnevåg" <[email-masked]>
    -    Signed-off-by: Andrew Morton <[email-masked]>
    +    Acked-by: Carlos Llamas <[email-masked]>
    +    Signed-off-by: Liam R. Howlett <[email-masked]>
    +    Link: https://lore.kernel.org/r/[email-masked]
    +    Signed-off-by: Greg Kroah-Hartman <[email-masked]>
     
      ## drivers/android/binder_alloc.c ##
     @@ drivers/android/binder_alloc.c: static struct binder_buffer *binder_alloc_new_buf_locked(
    @@ drivers/android/binder_alloc.c: void binder_alloc_print_pages(struct seq_file *m
     -		}
     +
     +	mmap_read_lock(alloc->vma_vm_mm);
    -+	if (binder_alloc_get_vma(alloc) == NULL)
    ++	if (binder_alloc_get_vma(alloc) == NULL) {
    ++		mmap_read_unlock(alloc->vma_vm_mm);
     +		goto uninitialized;
    + 	}
     +
    ++	mmap_read_unlock(alloc->vma_vm_mm);
     +	for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
     +		page = &alloc->pages[i];
     +		if (!page->page_ptr)
    @@ drivers/android/binder_alloc.c: void binder_alloc_print_pages(struct seq_file *m
     +			active++;
     +		else
     +			lru++;
    - 	}
    ++	}
     +
     +uninitialized:
    -+	mmap_read_unlock(alloc->vma_vm_mm);
      	mutex_unlock(&alloc->mutex);
      	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
      	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);

-- 
Cheers,
Stephen Rothwell