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d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9vrg7EhUgrz2VdstxenWZe+fFP5TU9hDojaa4QJfF8Q=; b=kJ1XlhQDFLW37lg85RGj8iBd5WkddgL/QgodQ5JVIGLX1hacBeYvIJ/dknCyVftkuh hQJzB5WDE2axrSqCeqp9r68/RIZlNf6ct0bYcZmuoAGWZkIyp/7pOjtKOjIljXMJAd8N XQafH9L/6L61q886737wNqBRmYyA9LuQBZ3rPpDbCr7Ky9bHSR8mXMjxfwhtXa55oU0U rjOcFTqsK36zJQkWyoaCZ0jh+IaURhINXuyvREz+B3lbfEAhPwqT5+csZEi7KbNhhhIR VDulObsfPeEhVMGqKmetIFlXs2mp/UIvTrHMUy8MUyE3uG1c/A5txllMfqJWHm9NHQDY SrVA== X-Gm-Message-State: AOAM531orxRIUmxhs6MkcaTLRvvBtdk2U83xrCCzk3B3EphYwjdVjnBO 6JQqbW95gs32LN8gLSl+TTbIJhMxRVFp6p3Vnk20YA== X-Google-Smtp-Source: ABdhPJzRGE0rsOwGqhxO5Txn/GqpQrCcaK3fAH7lCRwMJgEYHd/TDNlGN8e9TKdGBSmDI6Sc9mVjt7HYkQK5W9W0egE= X-Received: by 2002:aca:d4d5:: with SMTP id l204mr10539438oig.70.1597689107235; Mon, 17 Aug 2020 11:31:47 -0700 (PDT) MIME-Version: 1.0 References: <20200807160627.GA1420741@elver.google.com> <20200807171849.GA1467156@elver.google.com> In-Reply-To: From: Marco Elver Date: Mon, 17 Aug 2020 20:31:35 +0200 Message-ID: Subject: Re: Odd-sized kmem_cache_alloc and slub_debug=Z To: Pekka Enberg Cc: Alexander Potapenko , Andrew Morton , David Rientjes , Joonsoo Kim , Christoph Lameter , Kees Cook , kasan-dev , LKML , "linux-mm@kvack.org" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 970BF28A4ED X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 7 Aug 2020 at 21:06, Pekka Enberg wrote: ... > Yeah, it reproduces with defconfig too, as long as you remember to > pass "slub_debug=Z"... :-/ > > The following seems to be the culprit: > > commit 3202fa62fb43087387c65bfa9c100feffac74aa6 > Author: Kees Cook > Date: Wed Apr 1 21:04:27 2020 -0700 > > slub: relocate freelist pointer to middle of object > > Reverting this commit and one of it's follow up fixes from Kees from > v5.8 makes the issue go away for me. Btw, please note that caches with > size 24 and larger do not trigger this bug, so the issue is that with > small enough object size, we're stomping on allocator metadata (I > assume part of the freelist). Was there a patch to fix this? Checking, just in case I missed it. Thanks, -- Marco