On Fri, May 14, 2021 at 07:22:47PM +0200, David Hildenbrand wrote: > Let's properly synchronize with drivers that set PageOffline(). > Unfreeze/thaw every now and then, so drivers that want to set PageOffline() > can make progress. > > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > fs/proc/kcore.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > index 92ff1e4436cb..982e694aae77 100644 > --- 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, ¬es_len, &data_offset); > phdrs_offset = sizeof(struct elfhdr); > @@ -480,6 +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; > @@ -565,6 +577,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > } > > out: > + page_offline_thaw(); > up_read(&kclist_lock); > if (ret) > return ret; > -- > 2.31.1 > -- Sincerely yours, Mike.