On Fri, 7 Aug 2015, Andrey Konovalov wrote: > > We are working on a dynamic data race detector for the Linux kernel > called KernelThreadSanitizer (ktsan) > (https://github.com/google/ktsan/wiki). > > While running ktsan on the upstream revision 21bdb584af8c with trinity > we got a few reports from SyS_swapon, here is one of them: > > ================================================================== > ThreadSanitizer: data-race in SyS_swapon > > Read of size 8 by thread T307 (K7621): > [< inlined >] SyS_swapon+0x3c0/0x1850 SYSC_swapon mm/swapfile.c:2395 > [<ffffffff812242c0>] SyS_swapon+0x3c0/0x1850 mm/swapfile.c:2345 > [<ffffffff81e97c8a>] ia32_do_call+0x1b/0x25 > > Looks like the swap_lock should be taken when iterating through the > swap_info array on lines 2392 - 2401. Thanks for the report. Actually, lines 2392 to 2401 just look redundant to me: it looks as if claim_swapfile() should do all that's needed, though in fact it doesn't quite. I'll send akpm a patch and Cc you, no need to retest since the offending lines just won't be there. 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>