Hi Ken,
On Thu, 26 Dec 2024 11:56:00 -0500
Ken Brown wrote:
> diff --git a/winsup/cygwin/mm/mmap.cc b/winsup/cygwin/mm/mmap.cc
> index 13418d782baf..10e3f5bdc2b3 100644
> --- a/winsup/cygwin/mm/mmap.cc
> +++ b/winsup/cygwin/mm/mmap.cc
> @@ -580,18 +580,61 @@ mmap_record::free_fh (fhandler_base *fh)
> delete fh;
> }
>
> +/* Keep the list of anonymous mappings sorted as follows: All attached
> + records come first, then those that are noreserve but not attached,
> + then those that are not noreserve. Those that are noreserve but
> + not attached are sorted by address. This order of the mappings is
> + used in mmap_is_attached_or_noreserve. Note: The code that follows
> + makes implicit use of the fact that attached maps are also
> + noreserve. */
> mmap_record *
> mmap_list::add_record (mmap_record &r)
> {
> - mmap_record *rec = (mmap_record *) ccalloc (HEAP_MMAP,
> - sizeof (mmap_record)
> - + MAPSIZE (PAGE_CNT (r.get_len ())) * sizeof (DWORD), 1);
> - if (!rec)
> + mmap_record *new_rec = (mmap_record *) ccalloc (HEAP_MMAP,
> + sizeof (mmap_record)
> + + MAPSIZE (PAGE_CNT (r.get_len ()))
> + * sizeof (DWORD), 1);
> + if (!new_rec)
> return NULL;
> - rec->init_page_map (r);
> + new_rec->init_page_map (r);
> +
> + bool new_attached = new_rec->attached ();
> + bool new_noreserve = new_rec->noreserve ();
> + caddr_t new_addr = new_rec->get_address ();
> +
> + LIST_WRITE_LOCK ();
This patch atempt to acquire lock despite the lock has been
already acquired. I think this is the cause of deadlock.
> + if (fd != -1 || LIST_EMPTY (&recs))
> + {
> + LIST_INSERT_HEAD (&recs, new_rec, mr_next);
> + goto out;
> + }
>
> - LIST_INSERT_HEAD (&recs, rec, mr_next);
> - return rec;
> + /* Now we're working on the anonymous list, which is non-empty. */
> + mmap_record *rec, *prev;
> + LIST_FOREACH (rec, &recs, mr_next)
> + {
> + prev = rec;
> + if (new_attached)
> + {
> + LIST_INSERT_HEAD (&recs, new_rec, mr_next);
> + goto out;
> + }
> + if (new_noreserve && (rec->attached ()
> + || (rec->noreserve ()
> + && new_addr > rec->get_address ())))
> + continue;
> + if (!new_noreserve && rec->noreserve ())
> + continue;
> + LIST_INSERT_BEFORE (rec, new_rec, mr_next);
> + goto out;
> + }
> +
> + /* If we get here, new_rec should be inserted at the end of the
> + list, and prev points to the last record. */
> + LIST_INSERT_AFTER (prev, new_rec, mr_next);
> +out:
> + LIST_WRITE_UNLOCK ();
> + return new_rec;
> }
>
> void
--
Takashi Yano <takashi.y...@nifty.ne.jp>
