The vmalloc() code uses vmalloc_sync_all() to synchronize changes to the global reference kernel PGD to task PGDs in certain rare cases, like register_die_notifier().
This use seems to be somewhat questionable, as most other vmalloc page table fixups are vmalloc_fault() driven, but nevertheless it's there and it's using the pgd_list. But we don't need the global list, as we can walk the task list under RCU. Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Waiman Long <[email protected]> Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/mm/fault.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 50342825f221..366b8232f4b3 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -235,23 +235,35 @@ void vmalloc_sync_all(void) for (address = VMALLOC_START & PMD_MASK; address >= TASK_SIZE && address < FIXADDR_TOP; address += PMD_SIZE) { - struct page *page; - spin_lock(&pgd_lock); - list_for_each_entry(page, &pgd_list, lru) { + struct task_struct *g, *p; + + spin_lock(&pgd_lock); /* Implies rcu_read_lock(): */ + + for_each_process_thread(g, p) { + struct mm_struct *mm; spinlock_t *pgt_lock; - pmd_t *ret; + pmd_t *pmd_ret; - /* the pgt_lock only for Xen */ - pgt_lock = &pgd_page_get_mm(page)->page_table_lock; + task_lock(p); + mm = p->mm; + if (!mm) { + task_unlock(p); + continue; + } + /* The pgt_lock is only used on Xen: */ + pgt_lock = &mm->page_table_lock; spin_lock(pgt_lock); - ret = vmalloc_sync_one(page_address(page), address); + pmd_ret = vmalloc_sync_one(mm->pgd, address); spin_unlock(pgt_lock); - if (!ret) + task_unlock(p); + + if (!pmd_ret) break; } + spin_unlock(&pgd_lock); } } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
