ajax at nwnk.net
Tue Sep 2 13:38:41 PDT 2008
On Tue, 2008-09-02 at 15:33 -0400, Daniel Drake wrote:
> We're running xserver-188.8.131.526 in the new OLPC OS build. I'm working
> on this bug: http://dev.laptop.org/ticket/8022
> When you open http://wiki.laptop.org/go/Hardware in our firefox-based
> web browser app, X crashes with this trace:
> Program received signal SIGSEGV, Segmentation fault.
> XvDestroyPixmap (pPix=0x0) at xvmain.c:348
> 348 pScreen = pPix->drawable.pScreen;
> #0 XvDestroyPixmap (pPix=0x0) at xvmain.c:348
> #1 0x0808119f in ProcCreatePixmap (client=0x9450950) at dispatch.c:1342
> #2 0x08085dbf in Dispatch () at dispatch.c:454
> #3 0x0806b63d in main (argc=7, argv=0xbfa7c494, envp=0x0) at main.c:441
> It looks like mozilla requests a large pixmap that cannot be allocated,
> then we try to destroy a NULL pixmap.
> The attached patch solves the X crash by not freeing the NULL pixmap.
> However, with that applied, the application crashes when loading that
> particular page (admittedly not as bad as killing all of X, but hey). It
> dies with these last words:
Attached patch looks correct, I've pushed it to master (and will cherry
it to 1.5, which is coming out any hour now, I promise).
> The program 'rainbow-daemon' received an X Window System error.
> This probably reflects a bug in the program.
> The error was 'BadAlloc (insufficient resources for operation)'.
> (Details: serial 11493 error_code 11 request_code 53 minor_code 0)
> (Note to programmers: normally, X errors are reported asynchronously;
> that is, you will receive the error a while after causing it.
> To debug your program, run it with the --sync command line
> option to change this behavior. You can then get a meaningful
> backtrace from your debugger if you break on the gdk_x_error() function.)
> Any comments on whether this is a bug in X, mozilla, or something else?
X has an unfortunate coordinate limit at 2^15-1 square. If the server
is asked to create something bigger it's well within its rights to
refuse. So the question is what that CreatePixmap request looks like:
if it's asking for something beyond the coordinate limits it's an app
bug, if not it's an X bug.
> Also, Jordan Crouse commented that it is strange that Xv is appearing in
> the call trace here. Does anyone have an explanation for this? My X
> knowledge so is minimal that I don't really know when Xv should or
> should not be used...
It's not strange. Xv attaches private data to (some) pixmaps, so if the
pixmap being deleted is an Xv pixmap, Xv needs to free that too; but, of
course, the only way to know if it's an Xv pixmap is to ask Xv, so we
just add XvDestroyPixmap to the call chain.
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