vt: drop bootmem/slab memory distinction

Bootmem is not used for the vt screen buffer anymore as slab is now
available at the time the console is initialized.

Get rid of the now superfluous distinction between slab and bootmem,
it's always slab.

This also fixes a kmalloc leak which Catalin described thusly:

Commit a5f4f52e ("vt: use kzalloc() instead of the bootmem allocator")
replaced the alloc_bootmem() with kzalloc() but didn't set vc_kmalloced to
1 and the memory block is later leaked.  The corresponding kmemleak trace:

unreferenced object 0xdf828000 (size 8192):
  comm "swapper", pid 0, jiffies 4294937296
  backtrace:
    [<c006d473>] __save_stack_trace+0x17/0x1c
    [<c000d869>] log_early+0x55/0x84
    [<c01cfa4b>] kmemleak_alloc+0x33/0x3c
    [<c006c013>] __kmalloc+0xd7/0xe4
    [<c00108c7>] con_init+0xbf/0x1b8
    [<c0010149>] console_init+0x11/0x20
    [<c0008797>] start_kernel+0x137/0x1e4

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/vt.c

@@ -770,14 +770,12 @@ int vc_allocate(unsigned int currcons)	/* return 0 on success */
 	    visual_init(vc, currcons, 1);
 	    if (!*vc->vc_uni_pagedir_loc)
 		con_set_default_unimap(vc);
-	    if (!vc->vc_kmalloced)
-		vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL);
+	    vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL);
 	    if (!vc->vc_screenbuf) {
 		kfree(vc);
 		vc_cons[currcons].d = NULL;
 		return -ENOMEM;
 	    }
-	    vc->vc_kmalloced = 1;
 	    vc_init(vc, vc->vc_rows, vc->vc_cols, 1);
 	    vcs_make_sysfs(currcons);
 	    atomic_notifier_call_chain(&vt_notifier_list, VT_ALLOCATE, &param);
@@ -913,10 +911,8 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	if (new_scr_end > new_origin)
 		scr_memsetw((void *)new_origin, vc->vc_video_erase_char,
 			    new_scr_end - new_origin);
-	if (vc->vc_kmalloced)
-		kfree(vc->vc_screenbuf);
+	kfree(vc->vc_screenbuf);
 	vc->vc_screenbuf = newscreen;
-	vc->vc_kmalloced = 1;
 	vc->vc_screenbuf_size = new_screen_size;
 	set_origin(vc);
 
@@ -995,8 +991,7 @@ void vc_deallocate(unsigned int currcons)
 		vc->vc_sw->con_deinit(vc);
 		put_pid(vc->vt_pid);
 		module_put(vc->vc_sw->owner);
-		if (vc->vc_kmalloced)
-			kfree(vc->vc_screenbuf);
+		kfree(vc->vc_screenbuf);
 		if (currcons >= MIN_NR_CONSOLES)
 			kfree(vc);
 		vc_cons[currcons].d = NULL;
@@ -2881,7 +2876,6 @@ static int __init con_init(void)
 		INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
 		visual_init(vc, currcons, 1);
 		vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
-		vc->vc_kmalloced = 0;
 		vc_init(vc, vc->vc_rows, vc->vc_cols,
 			currcons || !vc->vc_sw->con_save_screen);
 	}

include/linux/console_struct.h

@@ -89,7 +89,6 @@ struct vc_data {
 	unsigned int	vc_need_wrap	: 1;
 	unsigned int	vc_can_do_color	: 1;
 	unsigned int	vc_report_mouse : 2;
-	unsigned int	vc_kmalloced	: 1;
 	unsigned char	vc_utf		: 1;	/* Unicode UTF-8 encoding */
 	unsigned char	vc_utf_count;
 		 int	vc_utf_char;