On 11/21/22 18:12, Vlastimil Babka wrote:
As explained in [1], we would like to remove SLOB if possible. - There are no known users that need its somewhat lower memory footprint so much that they cannot handle SLUB (after some modifications by the previous patches) instead. - It is an extra maintenance burden, and a number of features are incompatible with it. - It blocks the API improvement of allowing kfree() on objects allocated via kmem_cache_alloc(). As the first step, rename the CONFIG_SLOB option in the slab allocator configuration choice to CONFIG_SLOB_DEPRECATED. Add CONFIG_SLOB depending on CONFIG_SLOB_DEPRECATED as an internal option to avoid code churn. This will cause existing .config files and defconfigs with CONFIG_SLOB=y to silently switch to the default (and recommended replacement) SLUB, while still allowing SLOB to be configured by anyone that notices and needs it. But those should contact the slab maintainers and linux-mm@xxxxxxxxx as explained in the updated help. With no valid objections, the plan is to update the existing defconfigs to SLUB and remove SLOB in a few cycles. To make SLUB more suitable replacement for SLOB, a CONFIG_SLUB_TINY option was introduced to limit SLUB's memory overhead. There is a number of defconfigs specifying CONFIG_SLOB=y. As part of this patch, update them to select CONFIG_SLUB and CONFIG_SLUB_TINY.
Hm I forgot - some of those defconfigs might not actually be for so tiny devices to need CONFIG_SLUB_TINY (or SLOB previously). For those it would make more sense to simply remove CONFIG_SLOB=y and leave it to the default choice, which is SLUB (without _TINY). Feel free to point those out to me and I'll adjust. Thanks.
[1] https://lore.kernel.org/all/b35c3f82-f67b-2103-7d82-7a7ba7521439@xxxxxxx/ Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Aaro Koskinen <aaro.koskinen@xxxxxx> Cc: Janusz Krzysztofik <jmkrzyszt@xxxxxxxxx> Cc: Tony Lindgren <tony@xxxxxxxxxxx> Cc: Jonas Bonn <jonas@xxxxxxxxxxxx> Cc: Stefan Kristiansson <stefan.kristiansson@xxxxxxxxxxxxx> Cc: Stafford Horne <shorne@xxxxxxxxx> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx> Cc: Rich Felker <dalias@xxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx> Cc: Conor Dooley <conor@xxxxxxxxxx> Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx> Cc: <linux-omap@xxxxxxxxxxxxxxx> Cc: <openrisc@xxxxxxxxxxxxxxxxxxxx> Cc: <linux-riscv@xxxxxxxxxxxxxxxxxxx> Cc: <linux-sh@xxxxxxxxxxxxxxx> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
