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

[Greg KH]

On Fri, Aug 19, 2022 at 01:35:04PM +0000, Liam Howlett wrote:
> * Greg KH <greg@xxxxxxxxx> [220819 04:55]:
> > 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 <greg@xxxxxxxxx> 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 <liam.howlett@xxxxxxxxxx>
> > >      
> > >       ## 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/20220810160209.1630707-1-Liam.Howlett@xxxxxxxxxx
> > >     -    Fixes: a43cfc87caaf ("android: binder: stop saving a pointer to the VMA")
> > >     -    Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> > >     +    Fixes: a43cfc87caaf (android: binder: stop saving a pointer to the VMA)
> > >     +    Cc: stable <stable@xxxxxxxxxx>
> > >          Reported-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> > >     -    Reported-by: <syzbot+a7b60a176ec13cafb793@xxxxxxxxxxxxxxxxxxxxxxxxx>
> > >     -    Acked-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
> > >     +    Reported-by: syzbot+a7b60a176ec13cafb793@xxxxxxxxxxxxxxxxxxxxxxxxx
> > >          Tested-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> > >     -    Cc: Minchan Kim <minchan@xxxxxxxxxx>
> > >     -    Cc: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
> > >     -    Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > >     -    Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
> > >     -    Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
> > >     -    Cc: Martijn Coenen <maco@xxxxxxxxxxx>
> > >     -    Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> > >     -    Cc: Todd Kjos <tkjos@xxxxxxxxxxx>
> > >     -    Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> > >     -    Cc: "Arve Hjønnevåg" <arve@xxxxxxxxxxx>
> > >     -    Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > >     +    Acked-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
> > >     +    Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> > >     +    Link: https://lore.kernel.org/r/20220810160209.1630707-1-Liam.Howlett@xxxxxxxxxx
> > >     +    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > >      
> > >       ## 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.
> > 
> 
> b3bb668f3dc6 is the older v1 of the patch [1]. d6f35446d076 from
> mm-hotfixes is the correct v2 version [2], although I don't think that's
> currently in mm-hotfixes-unstable.  It looks like version 1 is now in
> mm-hotfixes-unstable as well.
> 
> 1: https://lore.kernel.org/linux-mm/20220809160618.1052539-1-Liam.Howlett@xxxxxxxxxx/
> 2: https://lore.kernel.org/linux-mm/20220810160209.1630707-1-Liam.Howlett@xxxxxxxxxx/

I'll let you and Andrew fight this one out :)