diff options
| -rw-r--r-- | include/linux/mmzone.h | 14 | ||||
| -rw-r--r-- | mm/sparse.c | 17 |
2 files changed, 20 insertions, 11 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index ec73582e7d27..2efd3be484fd 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1799,6 +1799,7 @@ static inline unsigned long section_nr_to_pfn(unsigned long sec) #define SUBSECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SUBSECTION_MASK) struct mem_section_usage { + struct rcu_head rcu; #ifdef CONFIG_SPARSEMEM_VMEMMAP DECLARE_BITMAP(subsection_map, SUBSECTIONS_PER_SECTION); #endif @@ -1992,7 +1993,7 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) { int idx = subsection_map_index(pfn); - return test_bit(idx, ms->usage->subsection_map); + return test_bit(idx, READ_ONCE(ms->usage)->subsection_map); } #else static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) @@ -2016,6 +2017,7 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) static inline int pfn_valid(unsigned long pfn) { struct mem_section *ms; + int ret; /* * Ensure the upper PAGE_SHIFT bits are clear in the @@ -2029,13 +2031,19 @@ static inline int pfn_valid(unsigned long pfn) if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; ms = __pfn_to_section(pfn); - if (!valid_section(ms)) + rcu_read_lock(); + if (!valid_section(ms)) { + rcu_read_unlock(); return 0; + } /* * Traditionally early sections always returned pfn_valid() for * the entire section-sized span. */ - return early_section(ms) || pfn_section_valid(ms, pfn); + ret = early_section(ms) || pfn_section_valid(ms, pfn); + rcu_read_unlock(); + + return ret; } #endif diff --git a/mm/sparse.c b/mm/sparse.c index 77d91e565045..338cf946dee8 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -792,6 +792,13 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, unsigned long section_nr = pfn_to_section_nr(pfn); /* + * Mark the section invalid so that valid_section() + * return false. This prevents code from dereferencing + * ms->usage array. + */ + ms->section_mem_map &= ~SECTION_HAS_MEM_MAP; + + /* * When removing an early section, the usage map is kept (as the * usage maps of other sections fall into the same page). It * will be re-used when re-adding the section - which is then no @@ -799,16 +806,10 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, * was allocated during boot. */ if (!PageReserved(virt_to_page(ms->usage))) { - kfree(ms->usage); - ms->usage = NULL; + kfree_rcu(ms->usage, rcu); + WRITE_ONCE(ms->usage, NULL); } memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr); - /* - * Mark the section invalid so that valid_section() - * return false. This prevents code from dereferencing - * ms->usage array. - */ - ms->section_mem_map &= ~SECTION_HAS_MEM_MAP; } /* |