Catalin and kmemleak spotted a leak of a VC screen buffer in
vc_allocate() due to the following chain of events:
vc_allocate()
visual_init(init=1)
vc->vc_sw->con_init(init=1)
fbcon_init()
vc_resize()
vc->screen_buf = kmalloc()
vc->screen_buf = kmalloc()
The common way for the VC drivers is to set the screen dimension
parameters manually in the init case and only call vc_resize() for
!init - which allocates a screen buffer according to the new
dimensions.
fbcon instead would do vc_resize() unconditionally and afterwards set
the dimensions manually (again) for !init - i.e. completely upside
down. The vc_resize() allocated buffer would then get lost by
vc_allocate() allocating a fresh one.
Use vc_resize() only for actual resizing to close the leak.
Set the dimensions manually only in initialization mode to remove the
redundant setting in resize mode.
The kmemleak trace from Catalin:
unreferenced object 0xde158000 (size 12288):
comm "Xorg", pid 1439, jiffies 4294961016
hex dump (first 32 bytes):
20 00 20 00 20 00 20 00 20 00 20 00 20 00 20 00 . . . . . . . .
20 00 20 00 20 00 20 00 20 00 20 00 20 00 20 00 . . . . . . . .
backtrace:
[<c006f74b>] __save_stack_trace+0x17/0x1c
[<c006f81d>] create_object+0xcd/0x188
[<c01f5457>] kmemleak_alloc+0x1b/0x3c
[<c006e303>] __kmalloc+0xdb/0xe8
[<c012cc4b>] vc_do_resize+0x73/0x1e0
[<c012cdf1>] vc_resize+0x15/0x18
[<c011afc1>] fbcon_init+0x1f9/0x2b8
[<c0129e87>] visual_init+0x9f/0xdc
[<c012aff3>] vc_allocate+0x7f/0xfc
[<c012b087>] con_open+0x17/0x80
[<c0120e43>] tty_open+0x1f7/0x2e4
[<c0072fa1>] chrdev_open+0x101/0x118
[<c006ffad>] __dentry_open+0x105/0x1cc
[<c00700fd>] nameidata_to_filp+0x2d/0x38
[<c00788cd>] do_filp_open+0x2c1/0x54c
[<c006fdff>] do_sys_open+0x3b/0xb4
Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Tested-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Johannes Weiner
0035fe00f7