Re: [lkml]Re: VM problems still in 2.2.18

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Fri Dec 15 2000 - 12:57:18 EST


> The changes in semaphore semantics are necessary to fix the spurious out of
> memory with MAP_SHARED mappings and they came together with the removal of the
> always-asynchronous kpiod. While it's certainly possible to remove it I don't
> think removing the fix for MAP_SHARED stuff is a good idea.

How hard is it to seperate losing kpiod (optimisation) from the MAP_SHARED
changes ? I am assuming they are two seperate issues, possibly wrongly

> Basically it's always safe to replace:
>
> down(&inode->i_sem);
> /* critical section */
> up(&inode->isem);
>
> with the new fs-semaphore:
>
> fs_down(&inode->i_sem);
> /* critical section */
> fs_up(&inode->i_sem);

Providing no inode semaphore is upped from a different task , which seems
currently quite a valid legal thing to do (ditto doing the up on completion of
something in bh or irq context)

Alan

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