linux-next: manual merge of the mm-unstable tree with the drm-misc-fixes tree

[Mark Brown]

Hi all,

Today's linux-next merge of the mm-unstable tree got a conflict in:

  drivers/gpu/drm/ttm/ttm_backup.c

between commit:

  a3fdf74ffa596 ("drm/ttm/pool: back up at native page order")

from the drm-misc-fixes tree and commit:

  c6bfdcf16f131 ("shmem: provide a shmem_write_folio wrapper")

from the mm-unstable tree.

I fixed it up (see below) 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.

diff --combined drivers/gpu/drm/ttm/ttm_backup.c
index 3c067aadc52de,c5b813a563e7f..0000000000000
--- a/drivers/gpu/drm/ttm/ttm_backup.c
+++ b/drivers/gpu/drm/ttm/ttm_backup.c
@@@ -6,10 -6,9 +6,10 @@@
  #include <drm/ttm/ttm_backup.h>
  
  #include <linux/export.h>
 -#include <linux/page-flags.h>
  #include <linux/swap.h>
  
 +#include "ttm_pool_internal.h"
 +
  /*
   * Need to map shmem indices to handle since a handle value
   * of 0 means error, following the swp_entry_t convention.
@@@ -69,23 -68,17 +69,23 @@@ int ttm_backup_copy_page(struct file *b
  }
  
  /**
 - * ttm_backup_backup_page() - Backup a page
 + * ttm_backup_backup_folio() - Backup a folio
   * @backup: The struct backup pointer to use.
 - * @page: The page to back up.
 - * @writeback: Whether to perform immediate writeback of the page.
 + * @folio: The folio to back up.
 + * @order: The allocation order of @folio.  Since TTM allocates higher-order
 + *         pages without __GFP_COMP, folio_nr_pages(@folio) would always
 + *         return 1; the caller must pass the true order explicitly.
 + * @writeback: Whether to perform immediate writeback of the folio's pages.
   * This may have performance implications.
 - * @idx: A unique integer for each page and each struct backup.
 + * @idx: A unique integer for the first page of the folio and each struct backup.
   * This allows the backup implementation to avoid managing
   * its address space separately.
 - * @page_gfp: The gfp value used when the page was allocated.
 - * This is used for accounting purposes.
 + * @folio_gfp: The gfp value used when the folio was allocated.
 + * Currently unused.
   * @alloc_gfp: The gfp to be used when allocating memory.
 + * @nr_pages_backed: Output. On a successful return, set to the number of
 + * pages actually backed up, which may be less than (1 << @order)
 + * if an -ENOMEM was encountered mid-folio.
   *
   * Context: If called from reclaim context, the caller needs to
   * assert that the shrinker gfp has __GFP_FS set, to avoid
@@@ -94,87 -87,53 +94,87 @@@
   * that the shrinker gfp has __GFP_IO set, since without it,
   * we're not allowed to start backup IO.
   *
 - * Return: A handle on success. Negative error code on failure.
 - *
 - * Note: This function could be extended to back up a folio and
 - * implementations would then split the folio internally if needed.
 - * Drawback is that the caller would then have to keep track of
 - * the folio size- and usage.
 + * Return: A handle for the first backed-up page on success (handles for
 + * subsequent pages follow sequentially). -ENOMEM if no pages could be backed
 + * up. Any other negative error code if a non-ENOMEM failure occurred; in that
 + * case any pages backed up so far are truncated before returning.
   */
  s64
 -ttm_backup_backup_page(struct file *backup, struct page *page,
 -		       bool writeback, pgoff_t idx, gfp_t page_gfp,
 -		       gfp_t alloc_gfp)
 +ttm_backup_backup_folio(struct file *backup, struct folio *folio,
 +			unsigned int order, bool writeback, pgoff_t idx,
 +			gfp_t folio_gfp, gfp_t alloc_gfp,
 +			pgoff_t *nr_pages_backed)
  {
  	struct address_space *mapping = backup->f_mapping;
 -	unsigned long handle = 0;
 +	int nr_pages = 1 << order;
  	struct folio *to_folio;
 -	int ret;
 +	int ret, i;
  
 -	to_folio = shmem_read_folio_gfp(mapping, idx, alloc_gfp);
 -	if (IS_ERR(to_folio))
 -		return PTR_ERR(to_folio);
 +	*nr_pages_backed = 0;
  
 -	folio_mark_accessed(to_folio);
 -	folio_lock(to_folio);
 -	folio_mark_dirty(to_folio);
 -	copy_highpage(folio_file_page(to_folio, idx), page);
 -	handle = ttm_backup_shmem_idx_to_handle(idx);
 +	for (i = 0; i < nr_pages; ) {
 +		int to_nr, j;
  
 -	if (writeback && !folio_mapped(to_folio) &&
 -	    folio_clear_dirty_for_io(to_folio)) {
 -		folio_set_reclaim(to_folio);
 -		ret = shmem_write_folio(to_folio);
 -		if (!folio_test_writeback(to_folio))
 -			folio_clear_reclaim(to_folio);
  		/*
 -		 * If writeout succeeds, it unlocks the folio.	errors
 -		 * are otherwise dropped, since writeout is only best
 -		 * effort here.
 +		 * Only inject past the first subpage so *nr_pages_backed is
 +		 * always > 0 here, matching a genuine mid-compound -ENOMEM
 +		 * and driving the caller's reactive split fallback instead
 +		 * of an early, no-progress failure.
  		 */
 -		if (ret)
 +		if (IS_ENABLED(CONFIG_FAULT_INJECTION) && i &&
 +		    ttm_backup_fault_inject_folio())
 +			to_folio = ERR_PTR(-ENOMEM);
 +		else
 +			to_folio = shmem_read_folio_gfp(mapping, idx + i, alloc_gfp);
 +		if (IS_ERR(to_folio)) {
 +			int err = PTR_ERR(to_folio);
 +
 +			if (err == -ENOMEM && *nr_pages_backed)
 +				return ttm_backup_shmem_idx_to_handle(idx);
 +
 +			if (*nr_pages_backed) {
 +				shmem_truncate_range(file_inode(backup),
 +						     (loff_t)idx << PAGE_SHIFT,
 +						     ((loff_t)(idx + i) << PAGE_SHIFT) - 1);
 +				/*
 +				 * The pages just truncated are no longer
 +				 * backed up; don't let the caller mistake
 +				 * them for valid handles.
 +				 */
 +				*nr_pages_backed = 0;
 +			}
 +			return err;
 +		}
 +
 +		to_nr = min_t(int, nr_pages - i,
 +			      folio_next_index(to_folio) - (idx + i));
 +
 +		folio_mark_accessed(to_folio);
 +		folio_lock(to_folio);
 +		folio_mark_dirty(to_folio);
 +
 +		for (j = 0; j < to_nr; j++)
 +			copy_highpage(folio_file_page(to_folio, idx + i + j),
 +				      folio_page(folio, i + j));
 +
 +		if (writeback && !folio_mapped(to_folio) &&
 +		    folio_clear_dirty_for_io(to_folio)) {
 +			folio_set_reclaim(to_folio);
++			ret = shmem_write_folio(to_folio);
 +			if (!folio_test_writeback(to_folio))
 +				folio_clear_reclaim(to_folio);
 +			if (ret == AOP_WRITEPAGE_ACTIVATE)
 +				folio_unlock(to_folio);
 +		} else {
  			folio_unlock(to_folio);
 -	} else {
 -		folio_unlock(to_folio);
 +		}
 +
 +		folio_put(to_folio);
 +		i += to_nr;
 +		*nr_pages_backed = i;
  	}
  
 -	folio_put(to_folio);
 -
 -	return handle;
 +	return ttm_backup_shmem_idx_to_handle(idx);
  }
  
  /**

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