Merge tag 'mtd/for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux

[linux-2.6-microblaze.git] / fs / proc / kcore.c

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index ed6fbb3..982e694 100644 (file)
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -313,6 +313,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 {
        char *buf = file->private_data;
        size_t phdrs_offset, notes_offset, data_offset;
+       size_t page_offline_frozen = 1;
        size_t phdrs_len, notes_len;
        struct kcore_list *m;
        size_t tsz;
@@ -322,6 +323,11 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
        int ret = 0;
 
        down_read(&kclist_lock);
+       /*
+        * Don't race against drivers that set PageOffline() and expect no
+        * further page access.
+        */
+       page_offline_freeze();
 
        get_kcore_size(&nphdr, &phdrs_len, &notes_len, &data_offset);
        phdrs_offset = sizeof(struct elfhdr);
@@ -465,6 +471,9 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 
        m = NULL;
        while (buflen) {
+               struct page *page;
+               unsigned long pfn;
+
                /*
                 * If this is the first iteration or the address is not within
                 * the previous entry, search for a matching entry.
@@ -477,6 +486,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
                        }
                }
 
+               if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
+                       page_offline_thaw();
+                       cond_resched();
+                       page_offline_freeze();
+               }
+
                if (&m->list == &kclist_head) {
                        if (clear_user(buffer, tsz)) {
                                ret = -EFAULT;
@@ -503,7 +518,16 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
                        }
                        break;
                case KCORE_RAM:
-                       if (!pfn_is_ram(__pa(start) >> PAGE_SHIFT)) {
+                       pfn = __pa(start) >> PAGE_SHIFT;
+                       page = pfn_to_online_page(pfn);
+
+                       /*
+                        * Don't read offline sections, logically offline pages
+                        * (e.g., inflated in a balloon), hwpoisoned pages,
+                        * and explicitly excluded physical ranges.
+                        */
+                       if (!page || PageOffline(page) ||
+                           is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
                                if (clear_user(buffer, tsz)) {
                                        ret = -EFAULT;
                                        goto out;
@@ -553,6 +577,7 @@ skip:
        }
 
 out:
+       page_offline_thaw();
        up_read(&kclist_lock);
        if (ret)
                return ret;