Please help, I think I see memory corruption with a driver recently added to linux-next.
The following error occur downloading a large file with wget (or ncftp): "read error: Bad address" wget exits and leaves the file unfinished. The error goes away when build_skb() is patched out, in this case by allocating pages directly in RX loop. I currently have two branches with code placed under ifdef USE_BUILD_SKB: https://bitbucket.org/Kasreyn/linux-next/src/faa7c408a655fdfd7c383f79259031da5a05d61e/drivers/net/ethernet/moxa/moxart_ether.c#cl-472 If build_skb() is the cause, is there something the driver can do about it? A quick search on "build_skb memory corruption" reveals the following commit, "igb: Revert support for build_skb in igb" f9d40f6a9921cc7d9385f64362314054e22152bd: "The reason for reverting this patch is that it can lead to data corruption. The following flow was pointed out by Ben Hutchings: 1. skb is forwarded to another device 2. Packet headers are modified and it's put into a queue 3. Second packet is received into the other half of this page 4. Page cannot be reused, so is DMA-unmapped 5. The DMA mapping was non-coherent, so unmap copies or invalidates cache The headers added in step 2 get trashed in step 5." This is extra interesting, errors only happen on a locally mounted ext3 filesystem, never on tmpfs e.g.: # mount /dev/mmcblk0p1 on / type ext3 (rw,relatime,errors=continue,barrier=1,data=ordered) tmpfs on /dev/shm type tmpfs (rw,relatime,mode=777) tmpfs on /tmp type tmpfs (rw,relatime) #cd /tmp # wget -c ftp://149.20.4.69/pub/linux/kernel/v2.6/linux-2.6.11.11.tar.gz Connecting to 149.20.4.69 (149.20.4.69:21) linux-2.6.11.11.tar. 25% |******* | 11374k 0:01:36 ETAwget: short write [ 153.560000] wget (383) used greatest stack depth: 4776 bytes left # rm linux-2.6.11.11.tar.gz # wget -c ftp://149.20.4.69/pub/linux/kernel/v2.6/linux-2.6.11.11.tar.gz Connecting to 149.20.4.69 (149.20.4.69:21) linux-2.6.11.11.tar. 25% |******* | 11315k 0:01:34 ETAwget: short write # rm linux-2.6.11.11.tar.gz # wget -c ftp://149.20.4.69/pub/linux/kernel/v2.6/linux-2.6.11.11.tar.gz Connecting to 149.20.4.69 (149.20.4.69:21) linux-2.6.11.11.tar. 25% |******* | 11473k 0:01:38 ETAwget: short write [ 237.300000] wget (387) used greatest stack depth: 4752 bytes left # cd /root/ # wget -c ftp://149.20.4.69/pub/linux/kernel/v2.6/linux-2.6.11.11.tar.gz Connecting to 149.20.4.69 (149.20.4.69:21) linux-2.6.11.11.tar. 3% |* | 1647k 0:03:02 ETA wget: read error: Bad address Regards, Jonas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
