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Andrea Arcangeli <andrea@suse.de> wrote: >> 1) The major one (the only one I believe that was triggering [only on > ext2 due the fact mpage is working only there]) is the marking of the bh > clean despite we could still run into the "confused" path. After that > the confused path really becomes confused and it writes nothing and fs > corruption triggers silenty (the reugular writepage only writes bh that > are marked dirty, it never attempts to submit_bh anything marked clean). > The mpage-writepage code must never mark the bh clean as far as it > wants to still fallback in the regular writepage which depends on the bh > to be dirty (i.e. the "goto confused" path). This could only triggers > with memory pressure (it also needs buffer_heads_over_limit == 0, and > that is frequent under mm pressure). ooh, nasty, yes. You must be testing the crap out if it. > 3) Third bug is in the regular writepage, the nr_underway == 0 code was > walking buffers on an unlocked page without keeping the bh pinned, and > in turn the bh could be released under it by the VM. Fix is to delay the > put_bh loop. (this might have triggered but it's not certain) PG_writeback protects the page from truncate, from invalidate and from page reclaim. pagevec_strip() won't touch the buffers due to the PageWriteback() test in try_to_release_page(). So I think we're OK in there. I can add a couple more coment fixes for this. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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