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

From: Greg KH <[email-masked]>
Date: Fri, 19 Aug 2022 10:55:30 +0200

On Fri, Aug 19, 2022 at 06:40:27PM +1000, Stephen Rothwell wrote:
> 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);
> 

Oh wow, ok, I'll go drop my version and assume that Andrew's is the more
correct one and let it come through his tree.

thanks,

greg k-h