mm/failslab.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/fault-inject.h>
   3 #include <linux/error-injection.h>
   4 #include <linux/debugfs.h>
   5 #include <linux/slab.h>
   6 #include <linux/mm.h>
   7 #include "slab.h"
   8
   9 static struct {
  10         struct fault_attr attr;
  11         bool ignore_gfp_reclaim;
  12         bool cache_filter;
  13 } failslab = {
  14         .attr = FAULT_ATTR_INITIALIZER,
  15         .ignore_gfp_reclaim = true,
  16         .cache_filter = false,
  17 };
  18
  19 int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
  20 {
  21         int flags = 0;
  22
  23         /* No fault-injection for bootstrap cache */
  24         if (unlikely(s == kmem_cache))
  25                 return 0;
  26
  27         if (gfpflags & __GFP_NOFAIL)
  28                 return 0;
  29
  30         if (failslab.ignore_gfp_reclaim &&
  31                         (gfpflags & __GFP_DIRECT_RECLAIM))
  32                 return 0;
  33
  34         if (failslab.cache_filter && !(s->flags & SLAB_FAILSLAB))
  35                 return 0;
  36
  37         /*
  38          * In some cases, it expects to specify __GFP_NOWARN
  39          * to avoid printing any information(not just a warning),
  40          * thus avoiding deadlocks. See commit 6b9dbedbe349 for
  41          * details.
  42          */
  43         if (gfpflags & __GFP_NOWARN)
  44                 flags |= FAULT_NOWARN;
  45
  46         return should_fail_ex(&failslab.attr, s->object_size, flags) ? -ENOMEM : 0;
  47 }
  48 ALLOW_ERROR_INJECTION(should_failslab, ERRNO);
  49
  50 static int __init setup_failslab(char *str)
  51 {
  52         return setup_fault_attr(&failslab.attr, str);
  53 }
  54 __setup("failslab=", setup_failslab);
  55
  56 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
  57 static int __init failslab_debugfs_init(void)
  58 {
  59         struct dentry *dir;
  60         umode_t mode = S_IFREG | 0600;
  61
  62         dir = fault_create_debugfs_attr("failslab", NULL, &failslab.attr);
  63         if (IS_ERR(dir))
  64                 return PTR_ERR(dir);
  65
  66         debugfs_create_bool("ignore-gfp-wait", mode, dir,
  67                             &failslab.ignore_gfp_reclaim);
  68         debugfs_create_bool("cache-filter", mode, dir,
  69                             &failslab.cache_filter);
  70
  71         return 0;
  72 }
  73
  74 late_initcall(failslab_debugfs_init);
  75
  76 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */