On (10/29/12 11:32), Nitin Gupta wrote: > > Nothing should be printed (even a debug only message) for > the ZRAM_ZERO case. This case can be quite common for certain > kinds of data and would cause a huge log spew. Also (!handle) case > is not the same as zero-filled page case, so this message would > be misleading. > > So, we should either get rid of this warning entirely or only do > pr_debug("Read before write ....") for (!handle) case and log nothing > for ZRAM_ZERO case. >
I'd rather remove this message. Will resend. By the way, about use after-free. I'm afraid you fix is not covering 100% of the cases. The problem is with this case: [..] 334 335 if (unlikely(clen > max_zpage_size)) { 336 zram_stat_inc(&zram->stats.bad_compress); 337 src = uncmem; 338 clen = PAGE_SIZE; 339 } 340 [..] where uncmem could be: -- kmap'ed page -- kmalloc'ed page both of which were unmap'ed/kfree'd before. you moved kfree to the end of the function, while kunmap_atomic(user_mem) is still happening before src = uncmem/memcpy(cmem, src, clen) pair. -ss -- 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/