Hi.

Actually, this is extracted from bug# 12712 at bugzilla.kernel.org.

drivers/video/vesafb.c

static int __init vesafb_probe(struct platform_device *dev)

	if (!request_mem_region(vesafb_fix.smem_start, size_total, "vesafb")) {
		printk(KERN_WARNING
		       "vesafb: cannot reserve video memory at 0x%lx\n",
			vesafb_fix.smem_start);
		/* We cannot make this fatal. Sometimes this comes from magic
		   spaces our resource handlers simply don't know about */
	}

	info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev);
	if (!info) {
		release_mem_region(vesafb_fix.smem_start, size_total);
		return -ENOMEM;
	}

My first question is why we cannot make request_mem_region failure fatal?
(Most framebuffers does.)

If we can't make request_mem_region error fatal, then my second question is - is it correct to call release_mem_region in case of unsuccessful framebuffer_alloc? The problem here is that we can release_mem_region which wasn't allocated by vesafb request_mem_region call. IMHO at least there should be some flag (e.g., bool) proving that request_mem_region was successful and it's "safe" to call release_mem_region. Otherwise it's possible to release "non-vesafb" memory region.

This leads to things like this (2 framebuffers on a single video card):

[    1.502011] nvidiafb: CRTC 0 is currently programmed for DFP
[    1.502022] nvidiafb: Using DFP on CRTC 0
[    1.502031] nvidiafb: Panel size is 1280 x 800
[    1.502040] nvidiafb: Panel is LVDS
[    1.505580] nvidiafb: MTRR set to ON
[    1.505599] fbcvt: 1280x800@60: CVT Name - 1.024MA-R
[    1.505856] fbcon: NV1d (fb0) is primary device
[    1.657379] nvidiafb: Flat panel dithering disabled
[    1.658735] Console: switching to colour frame buffer device 160x50
[    1.659929] nvidiafb: PCI nVidia NV1d framebuffer (64MB @ 0xC0000000)
[    1.660099] vesafb: cannot reserve video memory at 0xc0000000
[    1.660386] vesafb: framebuffer at 0xc0000000, mapped to 0xfd180000, using
6144k, 
total 131072k
[    1.660419] vesafb: mode is 1024x768x32, linelength=4096, pages=1
[    1.660445] vesafb: protected mode interface info at c000:d5d0
[    1.660471] vesafb: pmi: set display start = c00cd606, set palette =
c00cd670
[    1.660498] vesafb: pmi: ports = 3b4 3b5 3ba 3c0 3c1 3c4 3c5 3c6 3c7 3c8 3c9
3cc 3ce 
3cf 3d0 3d1 3d2 3d3 3d4 3d5 3da
[    1.660714] vesafb: scrolling: redraw
[    1.660734] vesafb: Truecolor: size=8:8:8:8, shift=24:16:8:0
[    1.660825] fb1: VESA VGA frame buffer device

Should I submit it as new bug at bugzilla.kernel.org?

Thanks.

Sergey.