Messages in this thread | | | Date | Thu, 27 Dec 2001 13:50:37 -0600 | From | Mark J Roberts <> | Subject | Framebuffer, mmap(), hanging in D state, root FS unmount failure. |
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#include <assert.h> #include <sys/mman.h> #include <fcntl.h> int main(void) { char *p; assert((p = mmap(0, 1, PROT_READ|PROT_WRITE, MAP_SHARED, open("/dev/fb/0", O_RDWR), 0)) != MAP_FAILED); p[4096] = 0; /* this hangs */ return 0; }
When I run this on my 2.4.17rc2aa2 kernel with a Voodoo3000 framebuffer, the process hangs forever in D state. ps and top will then hang the same way when they read the /proc/pid files for the hung process. And my root filesystem won't unmount.
It only happens when PROT_READ|PROT_WRITE is specified - when I use only PROT_WRITE, the program segfaults like you'd expect.... but once the PROT_READ|PROT_WRITE version has hung, PROT_WRITE-only versions will also hang. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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