diff options
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 43 |
1 files changed, 29 insertions, 14 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0745aedebb37..7d980dc0000e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1356,6 +1356,8 @@ out: * see the comment next to it. * 3. Skipping poisoning is requested via __GFP_SKIP_KASAN_POISON, * see the comment next to it. + * 4. The allocation is excluded from being checked due to sampling, + * see the call to kasan_unpoison_pages. * * Poisoning pages during deferred memory init will greatly lengthen the * process and cause problem in large memory systems as the deferred pages @@ -2468,7 +2470,8 @@ inline void post_alloc_hook(struct page *page, unsigned int order, { bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) && !should_skip_init(gfp_flags); - bool init_tags = init && (gfp_flags & __GFP_ZEROTAGS); + bool zero_tags = init && (gfp_flags & __GFP_ZEROTAGS); + bool reset_tags = !zero_tags; int i; set_page_private(page, 0); @@ -2491,30 +2494,42 @@ inline void post_alloc_hook(struct page *page, unsigned int order, */ /* - * If memory tags should be zeroed (which happens only when memory - * should be initialized as well). + * If memory tags should be zeroed + * (which happens only when memory should be initialized as well). */ - if (init_tags) { + if (zero_tags) { /* Initialize both memory and tags. */ for (i = 0; i != 1 << order; ++i) tag_clear_highpage(page + i); - /* Note that memory is already initialized by the loop above. */ + /* Take note that memory was initialized by the loop above. */ init = false; } if (!should_skip_kasan_unpoison(gfp_flags)) { - /* Unpoison shadow memory or set memory tags. */ - kasan_unpoison_pages(page, order, init); - - /* Note that memory is already initialized by KASAN. */ - if (kasan_has_integrated_init()) - init = false; - } else { - /* Ensure page_address() dereferencing does not fault. */ + /* Try unpoisoning (or setting tags) and initializing memory. */ + if (kasan_unpoison_pages(page, order, init)) { + /* Take note that memory was initialized by KASAN. */ + if (kasan_has_integrated_init()) + init = false; + /* Take note that memory tags were set by KASAN. */ + reset_tags = false; + } else { + /* + * KASAN decided to exclude this allocation from being + * poisoned due to sampling. Skip poisoning as well. + */ + SetPageSkipKASanPoison(page); + } + } + /* + * If memory tags have not been set, reset the page tags to ensure + * page_address() dereferencing does not fault. + */ + if (reset_tags) { for (i = 0; i != 1 << order; ++i) page_kasan_tag_reset(page + i); } - /* If memory is still not initialized, do it now. */ + /* If memory is still not initialized, initialize it now. */ if (init) kernel_init_pages(page, 1 << order); /* Propagate __GFP_SKIP_KASAN_POISON to page flags. */ |