Hi Matteo,

On Mon, May 26, 2025 at 07:43:08PM +0200, Matteo Croce wrote:

s/PP/P/g

+.B struct cachestat_range {
+.BR "    __u64 off;"

Since these lines only have 1 argument, s/BR/B/g.

See groff_man(7):

     .B [text]
            Set text in bold.  If no argument is given, a one‐line in‐
            put trap is planted; text on the next line, which can be
            further formatted with a macro, is set in bold.

     .BR bold‐text roman‐text ...
            Set each argument in bold and roman, alternately.

+.BR "    __u64 len;"
+.RE

This RE is spurious.

+.B };
+.PP
+.B struct cachestat {
+.BR "    __u64 nr_cache;"
+.BR "    __u64 nr_dirty;"
+.BR "    __u64 nr_writeback;"
+.BR "    __u64 nr_evicted;"
+.BR "    __u64 nr_recently_evicted;"
+.B };
+.PP
+.BI "int cachestat(unsigned int " fd ", struct cachestat_range *" cstat_range ","
+.br

This br is spurious.

+.BI "              struct cachestat *" cstat ", unsigned int " flags ");"
+.nf
+.SH DESCRIPTION
+.B cachestat()
+queries the number of cached pages, dirty pages,
+pages marked for writeback, evicted pages,
+and recently evicted pages in the byte range specified by
+.I .off
+and
+.I .len
+in the
+.B cachestat_range
+structure.
+.P
+An evicted page is one that was previously in the page cache
+but has since been evicted.
+A page is considered recently evicted if its reentry into the cache
+would indicate active usage under memory pressure.
+.PP
+The results are returned in a
+.B cachestat
+structure, pointed to by the
+.I cstat
+argument.
+.PP
+The
+.I .off
+and
+.I .len
+fields must be non-negative. If

s/\. /.\n/

+.I .len > 0
+, the queried range is

The comma should go in the previous line.  Otherwise, it creates a
spurious space.

	.IR .len\~>\~0 ,

+.RI [ .off ,\~ .off+.len ]
+. If
+.IR len\~==\~0 ,
+the range is from
+.I .off
+to the end of the file.
+.PP
+The
+.I flags
+argument is reserved for future use and must be set to
+.BR 0 .
+.
+.PP
+Currently,
+.B hugetlbfs
+files are not supported.
+.PP
+Note that the status of a page may change after
+.B cachestat()
+retrieves it but before the values are returned to the application;
+thus, the values may be slightly outdated.

I'd move the paragraph from above to a CAVEATS section (see
man-pages(7)).

+.SH RETURN VALUE
+On success,
+.B cachestat()
+returns 0. On error, \-1 is returned and

s/\. /.\n/

s/ and/,\nand/

+.I errno
+is set appropriately.
+.SH ERRORS
+.TP
+.B EFAULT
+.I cstat
+or
+.I cstat_range
+point to an invalid address.
+.TP
+.B EINVAL
+Invalid
+.I flags
+value.
+.TP
+.B EBADF
+Invalid file descriptor.
+.TP
+.B EOPNOTSUPP
+The file descriptor refers to a
+.B hugetlbfs
+file, which is unsupported.

Please add STANDARDS and HISTORY sections.  You can have a look at
membarrier(2) for this:

	$ man -w membarrier | xargs mansect '(STANDARDS|HISTORY)' | tail -n+3;
	.SH STANDARDS
	Linux.
	.SH HISTORY
	Linux 4.3.
	.P
	Before Linux 5.10, the prototype was:
	.P
	.in +4n
	.EX
	.BI "int membarrier(int " cmd ", int " flags );
	.EE
	.in

-- 
2.49.0

Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es/>