Hello, On Thu, May 19, 2011 at 09:53:12AM +0200, Ludovic Desroches wrote: > There is a bug with the atmel-mci driver when the debug feature > CONFIG_DEBUG_VM is set. for the new audience: the driver does the following: flush_dcache_page(sg_page(sg)); with sg being a struct scatterlist * provided by the caller of the struct mmc_host_ops.request callback. > Into the atmci_read_data_pio function we use flush_dcache_page (do > we really need it?) which call the page_mapping function where we > can find VM_BUG_ON(PageSlab(Page)). Then a kernel panic happens. > > I don't understand the purpose of the VM_BUG_ON(PageSlab(Page)) (the > page comes from a scatter list). How could I correct this problem? I discussed this problem with Steven and Peter on irc and Steven found two functions in the mmc code (mmc_send_cxd_data and mmc_send_bus_test) that use the following idiom: struct scatterlist sg; void *data_buf; data_buf = kmalloc(len, GFP_KERNEL); sg_init_one(&sg, data_buf, len); Is that allowed (i.e. pass kmalloc'd memory to sg_init_one)? That might be the source of the slub page in the scatterlist, no? Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>