On Mon, 3 Feb 2014, Andrew Morton wrote: > On Mon, 27 Jan 2014 18:03:04 +0800 Weijie Yang <weijie.yang@xxxxxxxxxxx> wrote: > > > When swapon the same S_ISBLK blockdev concurrent, the allocated two > > swap_info could hold the same block_device, because claim_swapfile() > > allow the same holder(here, it is sys_swapon function). > > > > To prevent this situation, This patch adds swap_lock protect to ensure > > we can find this situation and return -EBUSY for one swapon call. > > > > As for S_ISREG swapfile, claim_swapfile() already prevent this scenario > > by holding inode->i_mutex. > > > > This patch is just for a rare scenario, aim to correct of code. > > > > hm, OK. Would it be saner to pass a unique `holder' to > claim_swapfile()? Say, `p'? > > Truly, I am fed up with silly swapon/swapoff races. How often does > anyone call these things? Let's slap a huge lock around the whole > thing and be done with it? That answer makes me sad: we can't be bothered to get it right, even when Weijie goes to the trouble of presenting a series to do so. But I sure don't deserve a vote until I've actually looked through it. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>