xfs: can't use kmem_zalloc() for attribute buffers

Because heap allocation of 64kB buffers will fail:

....
 XFS: fs_mark(8414) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8417) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8409) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8428) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8430) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8437) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8433) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8406) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8412) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8432) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
 XFS: fs_mark(8424) possible memory allocation deadlock size 65768 in kmem_alloc (mode:0x2d40)
....

I'd use kvmalloc() instead, but....

- 48.19% xfs_attr_create_intent
  - 46.89% xfs_attri_init
     - kvmalloc_node
	- 46.04% __kmalloc_node
	   - kmalloc_large_node
	      - 45.99% __alloc_pages
		 - 39.39% __alloc_pages_slowpath.constprop.0
		    - 38.89% __alloc_pages_direct_compact
		       - 38.71% try_to_compact_pages
			  - compact_zone_order
			  - compact_zone
			     - 21.09% isolate_migratepages_block
				  10.31% PageHuge
				  5.82% set_pfnblock_flags_mask
				  0.86% get_pfnblock_flags_mask
			     - 4.48% __reset_isolation_suitable
				  4.44% __reset_isolation_pfn
			     - 3.56% __pageblock_pfn_to_page
				  1.33% pfn_to_online_page
			       2.83% get_pfnblock_flags_mask
			     - 0.87% migrate_pages
				  0.86% compaction_alloc
			       0.84% find_suitable_fallback
		 - 6.60% get_page_from_freelist
		      4.99% clear_page_erms
		    - 1.19% _raw_spin_lock_irqsave
		       - do_raw_spin_lock
			    __pv_queued_spin_lock_slowpath
	- 0.86% __vmalloc_node_range
	     0.65% __alloc_pages_bulk

.... this is just yet another reminder of how much kvmalloc() sucks.
So lift xlog_cil_kvmalloc(), rename it to xlog_kvmalloc() and use
that instead....

We also clean up the attribute name and value lengths as they no
longer need to be rounded out to sizes compatible with log vectors.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_attr_item.c b/fs/xfs/xfs_attr_item.c
index 56f678c..e8ac88d 100644 (file)
--- a/fs/xfs/xfs_attr_item.c
+++ b/fs/xfs/xfs_attr_item.c
@@ -44,7 +44,7 @@ xfs_attri_item_free(
        struct xfs_attri_log_item       *attrip)
 {
        kmem_free(attrip->attri_item.li_lv_shadow);
-       kmem_free(attrip);
+       kvfree(attrip);
 }
 
 /*
@@ -119,11 +119,11 @@ xfs_attri_item_format(
                        sizeof(struct xfs_attri_log_format));
        xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTR_NAME,
                        attrip->attri_name,
-                       xlog_calc_iovec_len(attrip->attri_name_len));
+                       attrip->attri_name_len);
        if (attrip->attri_value_len > 0)
                xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTR_VALUE,
                                attrip->attri_value,
-                               xlog_calc_iovec_len(attrip->attri_value_len));
+                               attrip->attri_value_len);
 }
 
 /*
@@ -163,26 +163,21 @@ xfs_attri_init(
 
 {
        struct xfs_attri_log_item       *attrip;
-       uint32_t                        name_vec_len = 0;
-       uint32_t                        value_vec_len = 0;
-       uint32_t                        buffer_size;
-
-       if (name_len)
-               name_vec_len = xlog_calc_iovec_len(name_len);
-       if (value_len)
-               value_vec_len = xlog_calc_iovec_len(value_len);
-
-       buffer_size = name_vec_len + value_vec_len;
+       uint32_t                        buffer_size = name_len + value_len;
 
        if (buffer_size) {
-               attrip = kmem_zalloc(sizeof(struct xfs_attri_log_item) +
-                                   buffer_size, KM_NOFS);
-               if (attrip == NULL)
-                       return NULL;
+               /*
+                * This could be over 64kB in length, so we have to use
+                * kvmalloc() for this. But kvmalloc() utterly sucks, so we
+                * use own version.
+                */
+               attrip = xlog_kvmalloc(sizeof(struct xfs_attri_log_item) +
+                                       buffer_size);
        } else {
-               attrip = kmem_cache_zalloc(xfs_attri_cache,
-                                         GFP_NOFS | __GFP_NOFAIL);
+               attrip = kmem_cache_alloc(xfs_attri_cache,
+                                       GFP_NOFS | __GFP_NOFAIL);
        }
+       memset(attrip, 0, sizeof(struct xfs_attri_log_item));
 
        attrip->attri_name_len = name_len;
        if (name_len)
@@ -195,7 +190,7 @@ xfs_attri_init(
        if (value_len)
                attrip->attri_value = ((char *)attrip) +
                                sizeof(struct xfs_attri_log_item) +
-                               name_vec_len;
+                               name_len;
        else
                attrip->attri_value = NULL;
 

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 70f718d..6ca6fe8 100644 (file)
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -135,39 +135,6 @@ xlog_cil_iovec_space(
 }
 
 /*
- * shadow buffers can be large, so we need to use kvmalloc() here to ensure
- * success. Unfortunately, kvmalloc() only allows GFP_KERNEL contexts to fall
- * back to vmalloc, so we can't actually do anything useful with gfp flags to
- * control the kmalloc() behaviour within kvmalloc(). Hence kmalloc() will do
- * direct reclaim and compaction in the slow path, both of which are
- * horrendously expensive. We just want kmalloc to fail fast and fall back to
- * vmalloc if it can't get somethign straight away from the free lists or buddy
- * allocator. Hence we have to open code kvmalloc outselves here.
- *
- * Also, we are in memalloc_nofs_save task context here, so despite the use of
- * GFP_KERNEL here, we are actually going to be doing GFP_NOFS allocations. This
- * is actually the only way to make vmalloc() do GFP_NOFS allocations, so lets
- * just all pretend this is a GFP_KERNEL context operation....
- */
-static inline void *
-xlog_cil_kvmalloc(
-       size_t          buf_size)
-{
-       gfp_t           flags = GFP_KERNEL;
-       void            *p;
-
-       flags &= ~__GFP_DIRECT_RECLAIM;
-       flags |= __GFP_NOWARN | __GFP_NORETRY;
-       do {
-               p = kmalloc(buf_size, flags);
-               if (!p)
-                       p = vmalloc(buf_size);
-       } while (!p);
-
-       return p;
-}
-
-/*
  * Allocate or pin log vector buffers for CIL insertion.
  *
  * The CIL currently uses disposable buffers for copying a snapshot of the
@@ -283,7 +250,7 @@ xlog_cil_alloc_shadow_bufs(
                         * storage.
                         */
                        kmem_free(lip->li_lv_shadow);
-                       lv = xlog_cil_kvmalloc(buf_size);
+                       lv = xlog_kvmalloc(buf_size);
 
                        memset(lv, 0, xlog_cil_iovec_space(niovecs));
 

diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 4f7e844..67fd978 100644 (file)
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -651,4 +651,38 @@ xlog_valid_lsn(
        return valid;
 }
 
+/*
+ * Log vector and shadow buffers can be large, so we need to use kvmalloc() here
+ * to ensure success. Unfortunately, kvmalloc() only allows GFP_KERNEL contexts
+ * to fall back to vmalloc, so we can't actually do anything useful with gfp
+ * flags to control the kmalloc() behaviour within kvmalloc(). Hence kmalloc()
+ * will do direct reclaim and compaction in the slow path, both of which are
+ * horrendously expensive. We just want kmalloc to fail fast and fall back to
+ * vmalloc if it can't get somethign straight away from the free lists or
+ * buddy allocator. Hence we have to open code kvmalloc outselves here.
+ *
+ * This assumes that the caller uses memalloc_nofs_save task context here, so
+ * despite the use of GFP_KERNEL here, we are going to be doing GFP_NOFS
+ * allocations. This is actually the only way to make vmalloc() do GFP_NOFS
+ * allocations, so lets just all pretend this is a GFP_KERNEL context
+ * operation....
+ */
+static inline void *
+xlog_kvmalloc(
+       size_t          buf_size)
+{
+       gfp_t           flags = GFP_KERNEL;
+       void            *p;
+
+       flags &= ~__GFP_DIRECT_RECLAIM;
+       flags |= __GFP_NOWARN | __GFP_NORETRY;
+       do {
+               p = kmalloc(buf_size, flags);
+               if (!p)
+                       p = vmalloc(buf_size);
+       } while (!p);
+
+       return p;
+}
+
 #endif /* __XFS_LOG_PRIV_H__ */