Let's properly synchronize with drivers that set PageOffline(). Unfreeze every now and then, so drivers that want to set PageOffline() can make progress.
Signed-off-by: David Hildenbrand <[email protected]> --- fs/proc/kcore.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 92ff1e4436cb..3d7531f47389 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -311,6 +311,7 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, static ssize_t read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) { + size_t page_offline_frozen = 0; char *buf = file->private_data; size_t phdrs_offset, notes_offset, data_offset; size_t phdrs_len, notes_len; @@ -509,6 +510,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) pfn = __pa(start) >> PAGE_SHIFT; page = pfn_to_online_page(pfn); + /* + * Don't race against drivers that set PageOffline() + * and expect no further page access. + */ + if (page_offline_frozen == MAX_ORDER_NR_PAGES) { + page_offline_unfreeze(); + page_offline_frozen = 0; + cond_resched(); + } + if (!page_offline_frozen++) + page_offline_freeze(); + /* * Don't read offline sections, logically offline pages * (e.g., inflated in a balloon), hwpoisoned pages, @@ -565,6 +578,8 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) } out: + if (page_offline_frozen) + page_offline_unfreeze(); up_read(&kclist_lock); if (ret) return ret; -- 2.30.2 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
