Index: sys/cam/ata/ata_da.c
===================================================================
--- sys/cam/ata/ata_da.c
+++ sys/cam/ata/ata_da.c
@@ -1081,6 +1081,8 @@
 		    (u_int8_t *) virtual,
 		    length,
 		    ada_default_timeout*1000);
+		ataio.ccb_h.xflags |= CAM_CCB_DUMP;
+
 		if ((softc->flags & ADA_FLAG_CAN_48BIT) &&
 		    (lba + count >= ATA_MAX_28BIT_LBA ||
 		    count >= 256)) {
@@ -1113,8 +1115,9 @@
 				    CAM_DIR_NONE,
 				    0,
 				    NULL,
-				    0,
+				    1,
 				    5*1000);
+		ataio.ccb_h.xflags |= CAM_CCB_DUMP;
 
 		if (softc->flags & ADA_FLAG_CAN_48BIT)
 			ata_48bit_cmd(&ataio, ATA_FLUSHCACHE48, 0, 0, 0);
Index: sys/cam/cam_ccb.h
===================================================================
--- sys/cam/cam_ccb.h
+++ sys/cam/cam_ccb.h
@@ -116,7 +116,8 @@
 typedef enum {
 	CAM_USER_DATA_ADDR	= 0x00000002,/* Userspace data pointers */
 	CAM_SG_FORMAT_IOVEC	= 0x00000004,/* iovec instead of busdma S/G*/
-	CAM_UNMAPPED_BUF	= 0x00000008 /* use unmapped I/O */
+	CAM_UNMAPPED_BUF	= 0x00000008,/* use unmapped I/O */
+	CAM_CCB_DUMP		= 0x00000010,/* polled ccb used during dump */
 } ccb_xflags;
 
 /* XPT Opcodes for xpt_action */
Index: sys/cam/cam_xpt.c
===================================================================
--- sys/cam/cam_xpt.c
+++ sys/cam/cam_xpt.c
@@ -190,6 +190,7 @@
 static struct cam_doneq cam_doneqs[MAXCPU];
 static int cam_num_doneqs;
 static struct proc *cam_proc;
+static STAILQ_HEAD(, ccb_hdr) cam_nondump_ccbs;
 
 SYSCTL_INT(_kern_cam, OID_AUTO, num_doneqs, CTLFLAG_RDTUN,
            &cam_num_doneqs, 0, "Number of completion queues/threads");
@@ -5480,6 +5481,21 @@
 		}
 	}
 
+	/*
+	 * Avoid completing non-dump I/O when we're dumping core after a panic.
+	 * Otherwise we may call into filesystem or pager code, potentially
+	 * resulting in a deadlock.  Note that this doesn't affect dumps that
+	 * were started manually since we aim to keep the system usable after it
+	 * has been resumed.
+	 */
+	if (__predict_false(dumping && SCHEDULER_STOPPED() &&
+	    ((ccb_h->xflags & CAM_CCB_DUMP) == 0))) {
+		STAILQ_INSERT_TAIL(&cam_nondump_ccbs, ccb_h, sim_links.stqe);
+		if ((ccb_h->status & CAM_DEV_QFRZN) != 0)
+			(void)cam_release_devq(ccb_h->path, 0, 0, 0, FALSE);
+		return;
+	}
+
 	if ((ccb_h->flags & CAM_UNLOCKED) == 0) {
 		if (mtx == NULL) {
 			mtx = xpt_path_mtx(ccb_h->path);
Index: sys/cam/nvme/nvme_da.c
===================================================================
--- sys/cam/nvme/nvme_da.c
+++ sys/cam/nvme/nvme_da.c
@@ -426,6 +426,7 @@
 		xpt_setup_ccb(&nvmeio.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
 		nvmeio.ccb_state = NDA_CCB_DUMP;
 		nda_nvme_write(softc, &nvmeio, virtual, lba, length, count);
+		nvmeio.ccb_h.xflags |= CAM_CCB_DUMP;
 		error = cam_periph_runccb((union ccb *)&nvmeio, cam_periph_error,
 		    0, SF_NO_RECOVERY | SF_NO_RETRY, NULL);
 		if (error != 0)
@@ -439,6 +440,7 @@
 
 	nvmeio.ccb_state = NDA_CCB_DUMP;
 	nda_nvme_flush(softc, &nvmeio);
+	nvmeio.ccb_h.xflags |= CAM_CCB_DUMP;
 	error = cam_periph_runccb((union ccb *)&nvmeio, cam_periph_error,
 	    0, SF_NO_RECOVERY | SF_NO_RETRY, NULL);
 	if (error != 0)
Index: sys/cam/scsi/scsi_da.c
===================================================================
--- sys/cam/scsi/scsi_da.c
+++ sys/cam/scsi/scsi_da.c
@@ -1847,6 +1847,8 @@
 				/*dxfer_len*/length,
 				/*sense_len*/SSD_FULL_SIZE,
 				da_default_timeout * 1000);
+		csio.ccb_h.xflags |= CAM_CCB_DUMP;
+
 		error = cam_periph_runccb((union ccb *)&csio, cam_periph_error,
 		    0, SF_NO_RECOVERY | SF_NO_RETRY, NULL);
 		if (error != 0)
@@ -1858,7 +1860,6 @@
 	 * Sync the disk cache contents to the physical media.
 	 */
 	if ((softc->quirks & DA_Q_NO_SYNC_CACHE) == 0) {
-
 		xpt_setup_ccb(&csio.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
 		csio.ccb_h.ccb_state = DA_CCB_DUMP;
 		scsi_synchronize_cache(&csio,
@@ -1869,6 +1870,8 @@
 				       /*lb_count*/0,
 				       SSD_FULL_SIZE,
 				       5 * 1000);
+		csio.ccb_h.xflags |= CAM_CCB_DUMP;
+
 		error = cam_periph_runccb((union ccb *)&csio, cam_periph_error,
 		    0, SF_NO_RECOVERY | SF_NO_RETRY, NULL);
 		if (error != 0)