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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1p1E1t-000YsR-9B; Fri, 02 Dec 2022 21:57:09 +0000 Date: Fri, 2 Dec 2022 21:57:09 +0000 From: Matthew Wilcox To: Thorsten Leemhuis Cc: bugzilla-daemon@kernel.org, linux-mm@kvack.org, Andrew Morton , decedion@gmail.com, mmp.dux@gmail.com Subject: Re: [Bug 216646] having TRANSPARENT_HUGEPAGE enabled hangs some applications (supervisor read access in kernel mode) Message-ID: References: <20221121125400.334190a6d2791b0c9afbfea0@linux-foundation.org> <220fd094-7cf1-9d17-8380-98d5663dc5da@leemhuis.info> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 30D3A8000F X-Stat-Signature: 3w9ccik4jnahuqoqarbbanmszxr5wwok X-Rspam-User: X-Spamd-Result: default: False [-3.47 / 9.00]; BAYES_HAM(-5.77)[99.51%]; SUSPICIOUS_RECIPS(1.50)[]; SUBJECT_HAS_UNDERSCORES(1.00)[]; R_DKIM_ALLOW(-0.20)[infradead.org:s=casper.20170209]; MIME_GOOD(-0.10)[text/plain]; RCVD_NO_TLS_LAST(0.10)[]; R_SPF_NA(0.00)[no SPF record]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; RCVD_COUNT_TWO(0.00)[2]; DKIM_TRACE(0.00)[infradead.org:+]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_FIVE(0.00)[6]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROMTLD(0.00)[]; TO_DN_SOME(0.00)[]; DMARC_NA(0.00)[infradead.org]; TAGGED_RCPT(0.00)[]; ARC_NA(0.00)[] X-Rspamd-Server: rspam08 X-HE-Tag: 1670018229-822090 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, Dec 02, 2022 at 04:58:42PM +0000, Matthew Wilcox wrote: > Landing on 793917d997df makes a lot more sense. That's where we > actually start using large folios. It doesn't really help narrow > down the problem. I have an idea for what it might be; patch to > try will follow. But I'll need feedback by email. This will give us a bit more information when it does happen. Further patch to catch it earlier will come "soon". diff --git a/lib/xarray.c b/lib/xarray.c index 6f47f6375808..b358b4e1dac6 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -6,6 +6,7 @@ * Author: Matthew Wilcox */ +#define XA_DEBUG #include #include #include @@ -207,6 +208,12 @@ static void *xas_descend(struct xa_state *xas, struct xa_node *node) if (xa_is_sibling(entry)) { offset = xa_to_sibling(entry); entry = xa_entry(xas->xa, node, offset); + + if (xa_is_sibling(entry)) { + printk("***BAD SIBLING*** index %ld offset %d\n", + xas->xa_index, offset); + xa_dump_node(node); + } } xas->xa_offset = offset;